Angry Shiites Muslims launched reprisal attacks on a Sunni mosque, political headquarters and several Baghdad neighborhoods, a day after a series of blasts and mortars killed more than 200 Shiites.
And a powerful Shiite bloc has threatened to pull its support from parliament if the prime minister meets next week in Jordan with President Bush.
Shiite revenge seekers wasted no time in striking Sunni Arab targets in retaliation for the deadliest series of attacks since the war began in 2003.
Despite a 24-hour curfew in Baghdad, mortars rained down on the Abu Hanifa mosque, an important Sunni shrine.
The first attack came Thursday evening shortly after the Sadr City attack, damaging the mosques dome.
Friday saw a second round of mortars, that police say injured one guard. At the headquarters of the influential Association of Muslim Scholars, more mortar rounds hit, injuring several guards.
And to the north of Baghdad in the city of Tal Afar, police say two suicide bombers detonated their explosives, killing at least 24 people and wounding several others inside a car dealership.
Meanwhile, militiamen clashed with U.S. forces Friday in the Shi'ite Sadr City neighborhood where Thursday's deadly bombings took place.
A U.S. spokesman told Reuters that he could not comment on specific operations but U.S. forces were helping Iraqi army and police enforce a curfew imposed after the attacks.
Also, in what would be a severe blow to Prime Minister Nouri al-Maliki's already shaky hold on power, Salah al-Eghali, a legislator from hard-line cleric Moqtada al-Sadr's bloc, says Sadr supporters will boycott parliament and the government if Mr. Maliki goes to Jordan next week for a planned meeting with President Bush.
Al-Sadr's followers hold six Cabinet seats and have 30 members in the 275-member parliament.
They blame the United States for Thursday's attack, saying American forces failed to provide security.
Earlier in the day, mourners made the dangerous journey 160-kilometers south to the Shiite holy city of Najaf to bury their dead under government-ordered police protection.
The prime minister and other politicians urged restraint and calm in the wake of the attacks, and called on all political groups to unite to protect their fellow Iraqis from such violence.