A spokesman for Maliki dismissed Mutlaq's comments, saying they are "not worthy of a response."
Mutlaq's Sunni-backed Iraqiya party has been boycotting parliament and cabinet meetings since last month to protest what it sees as efforts by Maliki to consolidate power, particularly over state security forces.
Maliki's government, meanwhile, has demanded the arrest of the country's top Sunni politician, Vice President Tariq al-Hashemi of Iraqiya, accusing him of running a hit squad targeting government officials.
Hashemi denies the allegations. He remains holed up in Iraq's semiautonomous northern Kurdish region. He is staying as a guest of Iraqi President Jalal Talabani, a Kurd, and is effectively out of reach of security forces under Baghdad's control.
Although Iraqiya is a nonsectarian party, it depends heavily on support from Sunnis.
The boycott and standoff over Hashemi have paralyzed Iraq's government, and pit the leaders of the country's mostly ethnic- and sectarian-based blocs against each other.
Iraq's Sunni minority dominated the government under the dictatorship of Saddam Hussein, but since he was overthrown, Shiites have controlled government.
The political feuding has been accompanied by bloody attacks, raising fears of a new sectarian rift that could destabilize Iraq now that U.S. troops have left the country. Many fear the crisis will push Iraq toward a renewal of the large-scale sectarian fighting that pushed the country to the brink of civil war in 2006-07.
The United States has been pushing Iraq's bickering factions to work out their differences.