Aide Hassan al-Zarqani said from Iran that al-Sadr will consult with Grand Ayatollah Ali al-Sistani and other top Shiite clerics on whether to disband the army, Reuters reported.
"If they order the Mahdi Army to disband, Muqtada al-Sadr and the Sadr movement will obey the orders of the religious leaders," he said.
The surprising news came the same day of Iraqi Prime Minister Nouri al-Maliki's televised demands that al-Sadr disband the army or his followers would be barred from upcoming elections.
Iraqi government spokesman Ali al-Dabbagh said he could not comment on the statement made by al-Sadr's aide, Reuters reported.
The Sadrists had earlier said banning them from elections would be unconstitutional, according to the Associated Press.
Al-Maliki launched a crackdown on the Mahdi Army two weeks ago in the southern city of Basra, prompting retaliatory fighting in Baghdad, particularly in Sadr City.
The fighting ebbed when al-Sadr ordered militia members off the streets but started again on Sunday in the Mahdi Army stronghold of Sadr City.
Al-Maliki said in a CNN interview that government troops would continue the Sadr City crackdown.
"We have opened the door for confrontation, a real confrontation with these gangs, and we will not stop until we are in full control of these areas," he said.
Meanwhile, the U.S. military announced the deaths of two more soldiers in roadside bombings on Sunday.