An Iranian Embassy convoy came under fire in Baghdad, wounding four people, including three Iranians and an Iraqi, a spokesman said Friday.

Tehran issued an angry response blaming the United States for encouraging attacks against Iranian interests in Iraq with its rhetoric against the Islamic republic. The U.S. military said it "condemns any attack on guests or visitors of any country."

It was not clear who shot at the convoy. An Iraqi Interior Ministry official said Iraqi soldiers exchanged fire with guards in an argument that broke out when members of the convoy failed to produce identification cards.

Iranian Embassy spokesman Manoucher Taslimi said he did not know who the gunmen were but said the convoy was attacked while it was en route to a revered Shiite shrine in the northern neighborhood of Kazimiyah.

The shooting comes as relations between Iraq's Shiite-led government and the rulers in neighboring Iran have come under unprecedented strains as Iraqi Prime Minister Nouri al-Maliki moves against rivals and negotiates long-term pacts with Washington.

The U.S. military also has stepped up allegations that Tehran is arming and funding Shiite militias who have been engaged in fierce clashes with American and Iraqi troops in Baghdad. Iran denies that it is fueling the violence in Iraq.

The shooting occurred about 5:30 p.m. Thursday as the convoy approached a bridge that links Kazimiyah with the predominantly Sunni area of Azamiyah, Taslimi said.

Taslimi said those wounded, including two Iranian diplomats and an Iranian and an Iraqi administrative employee, were in stable condition.

The Interior Ministry official said five people were wounded when the two-vehicle Iranian convoy exchanged fire with Iraqi soldiers at a checkpoint near the bridge after most of the Iranians failed to produce identification cards.

"The checkpoint staff asked them for ID cards, but nobody had one except for one Iranian called Abu al-Fadhil," the official said, speaking on condition of anonymity because he wasn't authorized to release the information.

Lt. David Russell, a U.S. military spokesman in Baghdad, said the Iraqi army had found four wounded Iranians in a vehicle with an Iraqi driver. The discrepancy in numbers could not immediately be reconciled.

Reports indicate the Iraqi security forces "handled the situation appropriately and with a high degree of professionalism, once again demonstrating their capability at maintaining security in their districts," Russell said in an e-mailed statement.

A spokesman for Iran's Foreign Ministry blamed the United States for the shooting, saying "the suspicious behavior of U.S. forces" has led to "increasing insecurity in Iraq."

"Responsibility for providing security to diplomats as well as diplomatic and international bodies in Iraq rests with the occupiers," Foreign Ministry spokesman Mohammad Ali Hosseini said Friday in a statement that was obtained by The Associated Press.

Hosseini said Iran will pursue the case with Iraqi government officials.

The U.S. military insisted the Americans were "in no way involved in this attack."

Meanwhile, the so-called "general military command" of the Mahdi Army militia that is loyal to anti-U.S. cleric Muqtada al-Sadr called on followers to adhere to an agreement reached this week to end clashes in Baghdad's Sadr City district.

In a statement circulated in the Mahdi Army stronghold before Friday prayers, the group praised the "resistance against occupation and tyranny."

But it called on them to "cease fire and obey orders and instructions" to prevent more bloodshed among Iraqi civilians.

"We are confident of your obedience to your leadership in spite of all the challenges, the statement said. "Let all hear, that if any party violates the agreement, we will have another attitude toward it."