In the Trump administration’s recent bellicose talk about Iran, Iraqis hear eerie echoes of the months just before the American invasion of Iraq.

Iraqi officials, wary of another war on their land, say they have warned armed groups tied to Iran to refrain from taking any action that could provoke American retaliation.

“The last two days there have been continuous meetings with all the groups to convey the Iraqi government’s message that if anyone does something, it is their responsibility, not Iraq’s,” said Sayed al-Jayashi, a senior member of Iraq’s National Security Council.

“The Iraqi government is responsible for protecting American interests in Iraq,” he added. “We will become the enemy of anyone who does something against American interests.”

President Trump spoke to American troops at Al Asad Air Base in Iraq in December.CreditAl Drago for The New York Times

President Trump spoke to American troops at Al Asad Air Base in Iraq in December.CreditAl Drago for The New York Times

The United States has not revealed any evidence supporting its assessment of an increased threat, though on Wednesday officials described what they said were photos of missiles being loaded onto Iranian boats. Allies of the United States have said that while Iran and its confederates may pose a danger, it is unclear whether there is a serious threat against American forces.

The claims have led many in the region to draw parallels to the Bush administration’s decision to go to war in 2003 based on false claims that Saddam Hussein had weapons of mass destruction.

There are about 30 militias in Iraq with at least 125,000 active-duty fighters and varying loyalties. Many worked in tandem with the Iraqi military in fighting the Islamic State, and all report to the prime minister’s office.

The concern in Iraq is focused on the handful of groups with strong ties to Iran. Several are close to Iran’s Revolutionary Guard Corps and have members who trained in Iran.

“Unfortunately we have groups that want to be more Iranian than Iran itself,” said Salah al-Obaidi, the spokesman for the populist cleric and power-broker Moktada al-Sadr. “We have concerns about the possibility that the government cannot control the pro-Iranian groups, and this will be a big problem in Iraq.”

He said the government needed to take a stronger stand against those groups.

“There is still no plan on the ground about what the government will do,” he said. “In the military there has to be strict rules and if anyone breaks the rules or does anything outside the plan, they are punished, and the government has not done that.”

Iraq, he said, cannot “be the place where America and Iran settle their scores.”

The parallels to 2003 do not escape anyone, but then important American allies like Britain and Japan supported the Bush administration in going to war; now the Trump administration’s hostility to Iran is a far lonelier stance.

Members of Iraq’s Popular Mobilization forces in a military exercise in Basra in January. Some of the militia groups are linked to Iran.CreditEssam Al-Sudani/Reuters

Members of Iraq’s Popular Mobilization forces in a military exercise in Basra in January. Some of the militia groups are linked to Iran.CreditEssam Al-Sudani/Reuters

Mr. Trump has long called the Iraq war a mistake, and has said that American forces should withdraw from the Middle East and other parts of the world. But his national security adviser, John R. Bolton, has advocated military strikes against Iran and regime change there. As a State Department official in 2003, he was seen as one of the more hawkish voices on Iraq.

On the streets of Baghdad, many Iraqis say that if there is an armed conflict between Iran or its proxies and the United States, it is more likely to take place in the Gulf rather than on Iraqi soil. Unlike the Iraq of 2003, Iraq today is an American ally.

“I am not afraid of a war between Iran and the United States,” said Ali Selim, 55, a barber who was drying his towels outdoors. “Then the American target was Iraq. This time it’s Iran,” he said, adding that the militias would not risk their own survival by provoking American retaliation because at the end of the day they are Iraqis.

Others dismissed the increased tensions between the United States and Iran as empty saber-rattling.

“It’s just talk, just threats,” said Salim Abu Hassan, 48, a worker who had just delivered a shipment of baby scales to a medical supply store. He said he had fought in the Iran-Iraq war in the 1980s, and was in Baghdad when the United States attacked 16 years ago. “Iran and America are each one trying to shout louder than the other.”

Mr. al-Jayashi, the Iraqi security council member, also said he believed that the Iranian government did not want war. But he said he worried about the Iranian Revolutionary Guard Corps acting on its own and possibly encouraging the armed groups it has fostered in the region to act on its behalf.

It can be difficult to discern Iran’s intentions since its elected leadership and government often sound reasonable, but the Revolutionary Guards and the Quds Force, whose leader Qassem Soleimani is in regular touch with Iraqi figures, take a far more antagonistic stance toward the United States.

However, Mr. al-Jayashi and other senior Iraqi officials said Iran’s only request to Iraq has been to prevent the United States from using its soil to launch an attack onIranian territory.

American soldiers in Iraq in 2003. Some hear echoes of the American case for war in Iraq in the Trump administration’s recent comments about Iran.CreditTyler Hicks/The New York Times

American soldiers in Iraq in 2003. Some hear echoes of the American case for war in Iraq in the Trump administration’s recent comments about Iran.CreditTyler Hicks/The New York Times

A senior Iraqi official who asked not to be identified said that the Americans had no plans to do that. The official said that Secretary of State Mike Pompeo, who visited Iraq last week, told Iraqi leaders that the United States respected Iraq’s sovereignty and that it would not launch attacks on Iran from Iraq.

The State Department did not immediately respond to a request for comment on Mr. Pompeo’s message to the Iraqis. Mr. Pompeo said that he had discussed the “importance of Iraq ensuring that it’s able to adequately protect Americans in their country.”

According to the official, Mr. Pompeo did not address whether the United States would launch an attack on Iraqi soil against an armed group that struck the United States, a scenario now under discussion at the Pentagon.

On Sunday, the United Arab Emirates reported that four oil tankers had been damaged in attacks off the Emirati coast. Two of them belonged to Saudi Arabia. Saudi Arabia and the U.A.E. — longtime antagonists of Iran’s — as well as the United States, have refrained from making public accusations or revealing what they know about the incidents, but privately, their officials have made clear that their suspicions focus on Iran.

American officials said Monday that there was no definitive evidence linking Iran or its proxies to the attacks.

But the British foreign secretary, Jeremy Hunt, warned this week of “the risk of a conflict happening by accident with an escalation that is unintended on either side.”

Such an escalation spilling into Iraq, which has been at war for most of the time since the American invasion, is a horror many Iraqis wish to believe could not happen again.

“I remember the destruction and the looting and the burned and destroyed buildings,” said Emad Hassan, 45. “We thought they came only to liberate Iraq, but they occupied it.”

An earlier version of this story referred incorrectly to Canada’s support for the Bush administration’s decision to invade Iraq in 2003. While Canada was a close ally during the Bush administration, it did not support the war in Iraq.