There are conflicting reports of the death toll, with figures ranging between five and 14 people.
The U.S. military said it targeted a house with "precision guided munitions" after three men suspected of planting a roadside bomb were seen entering the building. The statement made no mention of casualties.
The provincial governor, Hamad Hamud al-Qaisi, said he will demand an official investigation.
(Reuters/AFP/AP/dpa)