Speaking from an undisclosed location in Najaf before the announcement that talks with the interim government had failed, al-Sadr questioned the legitimacy of Iyad Allawi's government and said he and his al-Mahdi army were fighting for the rights of all Iraqis.
"This is the desire of the Iraqi people and I am here fighting for them," he said, referring to his demands on Friday that the interim Iraqi government should resign.
"I am a part of the people and I am a brother to them in this world and the next".
"This is a government propped up by the Americans," he said.
When asked if he was seeking any political office in any future reconciliation government, al-Sadr said he would not seek any official post, "not now, and until I die".
"I refused to participate in their so-called national meeting which is why I ... we are targeted. I will not participate in any political discourse as long as there is an occupation," he added.
Not Shia, not Muslims
Al-Sadr told Aljazeera this was not the first time he faced such difficult circumstances - having fought against government troops during the Shia uprising of March 1991, which was quickly suppressed by Saddam Hussein's forces.
He also went on to describe those Shia who reportedly demanded he should withdraw from Najaf, as non-Muslim.
"These people are not Shia, they are outside the teachings of Islam," he said.
"No one in his right mind could call Saddam a Muslim, but what these people are doing is far worse than what Saddam did to Iraq.
"It is not just the figure of Saddam; every Saddam, every government which [shows aggression] against the Iraqi people in this despicable manner by cooperating with the occupation must be removed," he added.
In an earlier speech made to his supporters, al-Sadr said the interim government was "a colonialist, imperialist extension of the US occupation of our lands".
"Najaf is witnessing victories against the forces of darkness, against the imperial colonists, by the grace of God.
"Despite all of this, we ask for peace, we ask for the right to live in liberty and justice … this is the will of the Iraqi people," he told Aljazeera.