US warplanes attacked targets in the town, and one US armoured vehicle was destroyed in the fighting on Thursday night, witnesses said on Friday.
"Fifteen Iraqis were killed and 20 were wounded," said Dr Issam Muhammad, a senior medical official.
Our correspondent Hamid Hadeed in Falluja reported that US forces bombed Jolan and Shuhada quarters.
Fierce clashes erupted overnight between the US forces and Iraqi resistance fighters. US aircraft dropped cluster bombs over Jolan, he said.
The city also came under intensive artillery bombardment.
US occupation troops have faced
fierce resistance in Falluja
US Marines launched their attack on Falluja on 5 April following the killing and mutilation of four US private security guards in the Sunni Muslim city the previous week.
Hundreds of Iraqis have died there in fighting since, said hospital officials.
Amidst the fighting, negotiations are still continuing for a total ceasefire between representatives of residents in Falluja and the Iraqi Islamic Party representing the Iraqi governing council, our correspondent said.
Last Friday the US occupation military said it had started a suspension of offensive operations in the city, but would fight back if attacked. There have been several rounds of talks on a truce, and fighting has been less intense this week.