BAGHDAD — Iraq’s prime minister got a show of support from political leaders of both Muslim sects yesterday as he moved to isolate the anti-American Shiite cleric, Muqtada al-Sadr, and his followers.

The meeting drew warnings from Sadrist lawmakers that the government’s effort against them could backfire even as fighting between Shiite militants and American-Iraqi forces eased somewhat after days of fierce clashes in Baghdad’s Sadr City district.

The fighting has taken its toll on all sides.

The American military announced that an American soldier was killed by a roadside bomb Wednesday in central Baghdad. This raise the number of Americans who died in Iraq the first 10 days of April to 18.

Prime Minister al-Maliki, himself a Shiite, convened the meeting of the main political blocs to discuss the Iraqi-led crackdown on militias that began March 25 in the southern city of Basra, triggering the current crisis.

But the notable absence of the Sadrists signaled that Mr. Maliki was making good on a threat to try to isolate the movement politically if its Mahdi Army militia is not disbanded.

The Sadrists complained they were not invited to the meeting. “The Iraqi prime minister is waging a political war,” a Sadrist lawmaker, Falah Shanshal, said. “But he is committing a big mistake because the Sadr movement enjoys the support of a large portion of the Iraqi public.”

The developments came a day after Iraqi authorities announced they would lift a 2-week-old vehicle ban on Sadr City and another Shiite militia stronghold, Shula, this weekend.

The intent is to provide relief to the residents who have suffered from food shortages as well as the violence.