At least five rockets hit the Iraqi military airbase at Balad north of Baghdad, wounding two Iraqi soldiers, the Iraqi military said in a statement.
Security officials had said earlier that the Katyusha rockets had fallen on the area of the base that houses US contractors, and that no casualties had been reported.
No group immediately claimed the attack on Sunday, but armed groups that some Iraqi officials say are backed by Iran have claimed similar incidents in the past.
US officials have blamed Iranian-backed militias for regular rocket attacks aimed at US facilities in Iraq, including the US Embassy in Baghdad.
The last attack on the Balad airbase was on April 4, when at least two rockets fell in the sparsely populated surrounding area.
F-16 aircraft are stationed at the airbase and several maintenance companies are present there, employing Iraqi and foreign staff.
The attack comes few days after an explosives-laden drone targeted US-led coalition forces near a northern Iraq airport, causing a large fire and damage to a building.
The incident was the latest in a string of attacks targeting mostly US installations in Iraq in recent weeks.
There have been about 20 bomb or rocket attacks against American interests, including bases hosting US soldiers, since US President Joe Biden took office in January.
Dozens of others took place from the autumn of 2019 under the administration of Donald Trump.
American forces withdrew from Iraq in 2011 but returned in 2014 at the invitation of Iraq to help battle ISIL (ISIS) after the group seized vast areas in the north and west of the country.
In late 2020, US troop levels in Iraq were reduced to 2,500 after withdrawals based on orders from the Trump administration.
Calls grew for further American troop withdrawals after a US-directed drone strike killed Iranian General Qassem Soleimani and an Iraqi militia leader in Baghdad in January 2020.
Last month, a base in western Iraq housing US-led coalition troops and contractors was hit by 10 rockets. One contractor was killed.
The US last week committed to withdrawing all remaining combat forces from Iraq, although the two countries did not set a timeline for what would be a second US withdrawal since the 2003 invasion which toppled Saddam Hussein.
The announcement came as the Biden administration resumed a “strategic dialogue” with the government of Prime Minister Mustafa al-Kadhimi, who is seen as too close to Washington by pro-Iranian groups.