Captain Bill Coppernoll said on Saturday the bombing was part of an operation called Cajun Mousetrap III.
The attack "was conducted to assist in the freedom of movement for Iraqi citizens and deny the enemy sanctuary in the surrounding area ... initial reports indicate that approximately 50 anti-Iraqi forces were killed", he said.
At least 13 Iraqis were also killed and 84 wounded in heavy overnight fighting between occupation troops and resistance fighters in Samarra.
"We have received 13 bodies including three women and two children and 84 injured," said doctor Abd Al-Hamid al-Samarrai of the city's general hospital - adding that many of the wounded were also women and children.
Police said more than 40 homes and several civilian vehicles were destroyed in the fighting as well as the municipal building and the offices of the political party of Iraqi Interior Minister Falah al-Naqib.
Mosques were heard urging people through loudspeakers to donate blood.
The US military confirmed it had conducted operations in the Sunni Muslim region, but refused to provide further details.
Iraqis have also been killed in clashes in Hilla between resistance fighters, Iraqi security forces and occupation troops.
Eight Iraqis were killed and 33 more wounded south of Baghdad in fierce clashes between Shia resistance fighters and Iraqi police and security forces backed by Polish occupation troops.
Victims in the heavy fighting in
Samarra on Friday
Police Chief Qais Hamza said on Saturday fighting began after a demonstration turned violent in the city of Hilla.
The dead and wounded were taken to two hospitals in the capital, where the toll was confirmed.
Meanwhile, about 20 Polish soldiers who were encircled in a police station have now returned to base, according to a spokesman for the army chief of staff in Warsaw.
Colonel Zdzislaw Gnatowski also confirmed that Polish tanks had taken up positions in front of provincial buildings in the town.
A US soldier and a marine have also died in separate attacks in the western province of al-Anbar, the military confirmed.
The soldier died of wounds he received on Friday "while conducting security and stability operations", it said. No details were given on the marine's death.
The latest casualties bring the number of US soldiers that have died in Iraq since its invasion to 938. As many as 37,000 Iraqi civilians may have died in the same period.