At least six Iraqis have been killed in a bomb explosion near a cafe in the capital, Baghdad, police say.
There is no sign of the violence abating
Officials said the target of the attack was a passing police patrol. Two of those killed were policemen. More than 20 people were injured in the blast.
On Monday, Iraqi and US troops clashed for seven hours with insurgents in Baghdad's Adhamiya district.
US troops were also involved in intense fighting in the city of Ramadi after an attack on a government building.
The violence comes as talks are stalled on a new national unity government.
Sunni, Kurdish and secular parties say they will not be partners in an administration headed by the current Shia-nominated Prime Minister Ibrahim Jaafari.
"Closely coordinated" attacks in Ramadi were repulsed on Monday, the US military said.
Ramadi and surrounding areas remain dangerous for US forces
A statement said attacks on the main government building and other sites involved "multiple homicide car bombs, mortars, rocket-propelled grenades, and heavy machine gun and small arms fire".
US Marine Capt Andrew Del Gaudio told the Associated Press news agency that troops fired on two suicide car bombers heading for the government building.
Reports from Ramadi suggest that around 60 gunmen took part in the offensive and that several were killed.
The attack shows that Ramadi and the surrounding Anbar province remain extremely dangerous areas for US forces, says the BBC's James Reynolds in Baghdad.
More than half the US soldiers killed this month have died in this region.
In Baghdad, the Iraqi army released further details of the seven-hour gun battle that took place on Monday in the Sunni Muslim-dominated Adhamiya neighbourhood in the north of the city.
It says that fighting began when an Iraqi army patrol came under fire before dawn.
About 50 targeted a checkpoint manned by the US army and the Iraqi police.
The battle ended after US reinforcements arrived. There were no US casualties.