The call was issued by Adnan Al-Dulaimi, a spokesman for the General Conference of Sunnis.
Sheikh Ibrahim al-Nima, a leading Sunni cleric from the main northern city of Mosul, said that sitting out the last elections was -- as he put it -- "a big mistake."
Sunni Arabs comprise around one-fifth of Iraq's 27 million people. They dominated during Saddam Hussein's regime.
New polls are scheduled for December after a new constitution has been drafted and put to a referendum. Voting could be delayed if agreement is slow on the new charter.