In the latest assault at the end of another day of violent unrest, Falluja's northern neighbourhood came under aerial assault on Tuesday night.
A witness said he heard about 15 bombing runs by US aircraft, striking the town some 50km west of Baghdad.
There was no immediate comment from the US military on possible casualties.
The air strike followed a major offensive launched by US forces on Baghdad's Sadr City and northern Babil in the south of the capital.
While American AC-130 warplanes attacked Sadr City - home to more than two million people - some 3000 US and Iraqi troops stormed northern Babil in an attempt to quell armed resistance.
Residents of Sadr City blame US
troops for the many deaths
"Iraqi and multinational forces today kicked off their most sweeping operation to date in northern Babil, moving against multiple targets across the central Iraqi province in a continuing campaign to restore security and stability here," a US military statement said.
The US military said 30 rebel fighters were captured in the first stage of the offensive.
To the immediate south of Baghdad, Babil province includes a series of mainly Sunni towns and is considered to be a stronghold of anti-US fighters.
At Sadr City, residents said US warplanes struck the neighbourhood repeatedly.
"I heard explosions. AC-130 planes were firing," said a resident, who added that he saw at least 12 tanks moving into the suburb.
An Iraqi journalist told Aljazeera that attempts by a US convoy to enter the suburb were repelled by fighters. Two explosive devices were detonated near the convoy.
A car bomb exploded on Tuesday as the Iraqi national guard was conducting raids in Yusufiya, a city south of Baghdad, killing at least one person and injuring 13, police said.
US-led forces are trying to quell
unrest before January polls
Nine guardsmen were among the wounded in Yusufiya, 20km south of the capital, said police Lieutenant Abbas Shashati.
The remaining dead and wounded were civilian bystanders, he said.
Earlier during the day an explosion rocked the crowded al-Nahda area in Baghdad, but no further details were available.
Another explosion was heard west of Baghdad, possibly in the Abu Ghraib area, an Iraqi journalist told Aljazeera. Further details could not be verified.
Iraqi interim Prime Minister Iyad Allawi vowed to restore order in the country.
"Our position is clear - people must abide by the law and put down their weapons.
"Otherwise the government will have to resort to force to provide peace to people," he said after meeting visiting British Foreign Secretary Jack Straw.
"We will not allow a few terrorists to hurt the Iraqi people," Allawi said.