Iraq's top Shiite cleric demanded an immediate cease-fire in Lebanon, warning Sunday that the Muslim world will "not forgive" nations that stand in the way of stopping the fighting.

Grand Ayatollah Ali al-Sistani issued the call following the Israeli airstrike that killed at least 56 Lebanese, mostly women and children, in the village of Qana. It was the deadliest attack in nearly three weeks of fighting.

"Islamic nations will not forgive the entities that hinder a cease-fire," al-Sistani said in a clear reference to the United States.

"It is not possible to stand helpless in front of this Israeli aggression on Lebanon," he added. "If an immediate cease-fire in this Israeli aggression is not imposed, dire consequences will befall the region."