Several blasts shook the Baghdad area hours after a huge funeral procession for a top Iranian general, killed by a US air strike there on Friday.
A projectile hit the Green Zone near the US embassy while several more were fired north of the Iraqi capital at Balad air base, which houses US forces.
Nobody was hurt in the attacks, Iraqi security sources said.
No group said it was behind the development. Pro-Iranian militants have been blamed for other recent attacks.
Iranian leaders have vowed to avenge the killing of Qasem Soleimani, who was regarded as a terrorist by the US.
President Trump warned on Twitter that the US is “targeting” 52 Iranian sites and will strike “very fast and very hard” if Tehran hits Americans or US assets.
Saturday’s funeral procession through Baghdad and Iraq’s Shia Muslim holy cities precedes the return of Soleimani’s remains to Iran.
Iraqis were also mourning the death of Abu Mahdi al-Muhandis, an Iraqi who commanded the Iranian-backed Kataib Hezbollah group and was killed along with Soleimani.
In another development, the group issued a warning to Iraqi security forces to “stay clear of American bases by a distance not less [than] 1,000m (0.6 miles) starting Sunday evening”, al-Mayadeen TV reported.
In response to Iranian threats of revenge, the US has sent 3,000 more troops to the Middle East and advised its citizens to leave Iraq.
What happened in the new attacks?
At least one rocket or mortar round hit Celebration Square in the Green Zone, while another exploded in the city’s Jadria area, Iraqi security sources said.
After two rockets hit Balad air base, surveillance drones were sent up to locate the source, AFP news agency reported.