Shiite cleric Moqtada Al Sadr called for calm on Sunday following suicide bombings on Shiites and said the first priority after last month's elections should be for occupation forces to leave.
Al Sadr, who led two bloody uprisings against US-led troops in April and August, also told Arab satellite television Al Jazeera that he would not take part in Iraq's political process as long as US-led forces remained.
Suicide bombings on Friday and Saturday killed at least 50 while Shiites were marking Ashura, the most important day in their religious calendar.
The attacks are believed to have been the work of Sunni militants determined to foment sectarian division and drive Iraq towards civil war.
"I ask all parties to show patience and not to be dragged into the plots of the West which aim to destabilise the country and justify the presence of the occupation," Al Sadr said.
"Any attack on any Iraqi group is an attack on all Iraqis ... and it is wrong for a Muslim to kill a Muslim."
The firebrand cleric, who has repeatedly condemned the ballot being held under occupation, said that if a new Iraqi government did not ask foreign forces to leave or set a timetable for their pullout, elections would have been useless.
"If elections open the door for the occupier to leave Iraq then it is a good thing. But if that is not the case, it will not have a real effect on the country or on Iraqis," he said.
"As long as the occupier is in Iraq, I will not take part in politics, whether in posts or the drafting of the constitution, because the occupier will intervene in one way or another."
But Al Sadr said all Iraqis should be allowed to participate in the political process, including minority Sunnis.
"We must help the minorities to have an effective role in building the future of Iraq. Everyone must be given a chance to participate in building Iraq," he said.
