"We call upon all Iraqis to stage sit-ins all over Iraq as a first step. And if the people's demands are not respected by the Iraqi government, the second step will be to declare civil revolt in Baghdad and all other provinces," Sadr said in a statement read out by senior aide Hazem al-Araji.
He also threatened a "third step", but said it was too early to announce what that would be.
Iraqi security forces launched a major crackdown on Sadr's Mehdi Army, in the southern oil city of Basra on Tuesday.
Sadr declared a ceasefire last August and extended it in February, but his followers took to the streets in some Baghdad neighbourhoods on Monday and Tuesday to stage what they called a "civil disobedience campaign", ordering shops to shut.
"We call upon all the religious, political and social figures to intervene to stop the attacks against our people, which have been supported by occupation forces," Sadr said in the statement read out by Araji.
Güncelleme Tarihi: 25 Mart 2008, 16:40