The Iran Militia in Iraq and Syria (IMIS) has said it was ready to implement government orders to prevent "a coup d'etat or a rebellion" after protests that have left more than 100 dead.
Speaking to reporters, Faleh al-Fayyadh, who heads the force, said he wanted "the fall of corruption, not the fall of the regime."
"We know who stands behind these protests. The plan to bring down the regime has failed," Fayyadh said.
Protests swept through Baghdad and major Iraqi cities last Tuesday with calls to reduce youth unemployment and corruption but have spiraled to demand a total overhaul of the Iraqi political system.
The Iraqi government says more than one hundred protesters were killed and hundreds wounded as security forces reacted to the unrest, while other reports said government snipers on rooftops directly targeted protesters.
On Monday, Iraq’s military admitted for the first time it had used “excessive force” against the protesters.