The attack on Baghdad's Green Zone involved at least seven mortar bombs, causing smoke to rise from buildings near the Iraqi parliament and government offices.
It was unclear if there were any casualties.
On the other side of the Tigris river on Tuesday, 87 people were killed by a lorry bomb which also partly demolished a Shia mosque.
The Green Zone, on the west side of the Tigris, is Baghdad's most secure area but has been a frequent target for rockets and mortar bombs.
The strikes have become more common and more accurate recently.
A mortar attack last week killed one employee of a hotel in the zone. There were also a number of casualties in April and May.
On April 12, a suicide bomber killed one politician in the parliament building in the worst breach of security in the zone since the March 2003 invasion to topple Saddam Hussein.