Salvoes of rockets were launched Friday at the US embassy in Baghdad's heavily fortified Green Zone, the mission said, the latest in a flurry of such attacks amid the Israel-Hamas war.
"A multi-rocket attack was launched at US and Coalition forces in the vicinity of Union III and the Baghdad embassy complex" without causing any reported casualties or damage, a US official said.
There was no immediate claim of responsibility. The United States leads an international coalition.
In a statement, the US embassy said "two salvoes of rockets" were fired at the mission compound at around 4:15 am (0115 GMT).
"Indications are the attacks were initiated by Iran-aligned militias," said a US spokesperson.
The spokesperson called on Iraq's government to protect diplomats, coalition partners and facilities, adding: "We reiterate that we reserve the right to self-defence and to protect our personnel anywhere in the world."
Iraqi Prime Minister Mohammed Shia al-Sudani warned that attacks on embassies undermine the country's security and called on security forces to bring those responsible to justice.
Since mid-October there have been dozens of rocket or drone strikes against US or coalition forces in Iraq.
An Iraqi security official said "three Katyusha rockets targeting the American embassy fell close to the Green Zone", near the river Tigris.
There are roughly 2,500 US troops in Iraq as part of efforts to prevent a resurgence of the IS group.
"Our security forces... will continue to protect embassies," the Iraqi premier said. His foreign affairs adviser, Farhad Alaaldin, said the government was "determined" to uphold Iraq's stability.
"No attempt to destabilise the country will be tolerated," he added.
The UN Assistance Mission for Iraq also condemned the attack and warned of repercussions.
"Iraq cannot afford to be drawn into a wider conflict, which would threaten hard-won stability and the achievements made so far," UNAMI said on X, formerly Twitter.