In a statement released on Wednesday, the US army confirmed that all three died at about 10pm (1900 GMT)following an ambush just outside the capital.
Their deaths bring the US toll in Iraq since the beginning of the latest war on Iraq to 1079. The latest ambush came as US warplanes continued to bomb Falluja through the night, killing at least six civilians.
One bombing raid completely destroyed the besieged town's most famous restaurant, killing the owner's son and nephew who had been looking after the shop during the night.
The second attack struck a house that had already been bombed before, flattening several homes in al-Askari neighbourhood as well as killing at least four members of an Iraqi family and injuring an unknown number of others.
Accusations and denials
An Iraqi journalist told Aljazeera the family was one of the few remaining in Falluja in that part of the city. Many have already fled because of continued US air strikes.
The US military said it was targeting a gathering of supporters of Abu Musab al-Zarqawi.
The journalist rejected the claim that al-Zarqawi used to eat at the targeted restaurant and visit the now-dead Iraqi family.
In nearby Ramadi, US troops raided several mosques and arrested Muslim scholar Shaikh Abd al-Alim al-Sadi and his son Usama.
Al-Sadi is a prominent member of the Association of Muslim Scholars, an organisation that has helped in negotiations between various Iraqi groups and troops.
US officials quoted by the New York Times have said they intend to invade Ramadi and Falluja, but may hold off until after the American presidential elections.