"Today the power is in the hands of the people and this means that we are not obliged to adopt principles imported from outside, thousands of miles from here," said Sheikh Sadr al-din al-Kubbanji, the Najaf head of the Supreme Council for the Islamic Revolution in Iraq.
"I think that if one seeks to impose a solution other what the Iraqi population wants, it would spark a crisis and none of the parties want this to happen," he added.
The Governing Council has been charged with writing the temporary constitution or fundamental law that will govern Iraq until national elections are held.
Many observers believe that some council members are pushing to implement Islamist rule in the post-occupation era.
Bremer vowed the new law would protect civil liberties in line with the agreement he reached with the Governing Council last November that set 30 June as the final day of the US-led occupation.
"Our position is clear, and the text that is in there now is as I say. It can not become law until I sign it," Bremer said.