Preachers called on their congregations to rally in Firdus Square on Saturday in central Baghdad where US troops helped haul down a statue of Saddam Hussein in footage that was beamed around the world.
Both Shia and Sunni leaders joined forces in calling for the protest.
"To mark the anniversary of the start of the occupation, I call on all Iraqis to demonstrate tomorrow in Firdus Square where Saddam's statue was toppled," said Shaikh Abd al-Zahra al-Suwaidi, a supporter of Shia leader Muqtada al-Sadr.
"The rally must be peaceful. You should demand the withdrawal of the occupation forces and press for quicker trials for Saddam Hussein and his aides before an Iraqi court," Suwaidi told worshippers in Baghdad's Sadr City.
Sunni clerics from the Association of Muslim Scholars (AMS), which organised a boycott of the January elections, urged followers to join the protest.
"I ask all Iraqis to join in peaceful demonstrations tomorrow against the occupation," said Shaikh Harith al-Dhari.
"The people must speak with one voice and say: 'No to the occupation; the occupiers must leave.'
"Two years have passed and all we see is bloodshed, destruction and looting."
The AMS has lines of communication to the Sunni Arab fighters operating in Iraq.
Fighters loyal to al-Sadr mounted two uprisings against US-led troops in central and southern Iraq last year before accepting a truce brokered by the Shia leadership.