Eyewitnesses said that the attack in Heet, 180 kilometres west of Baghdad, had also wounded another soldier.
One witness added that the US troops retreated from their position outside the local police station.
The attack came during another day of violence that saw the occupying armies sustain casualties across the country.
Six US soldiers were injured when their armoured vehicle came under fire from rocket propelled grenades in Mosul, eywitnesses told Aljazeera.
In Tikrit, Saddam Hussein's hometown, four more US soldiers were wounded in a mortar attack on their base outside the former president's palace.
Aljazeera's correspondent also reported a US fighter plane strike against what appeared to be a civilian vehicle north of the town.
An eyewitness said the target was completely destroyed but only after its occupants had fled.
Basra flares up
British troops in riot gear deployed in Basra on Saturday morning to quell spreading disturbances sparked by shortages of petrol and power in Iraq's second city, a British military spokesman said.
Witnesses said angry Iraqis threw stones, attacked cars registered in nearby Kuwait and burned tyres. Several streets and main roads leading into the city were cut as black smoke rose from the fires.
"We are taking measures to control the crowd."
British Army spokesman
British forces fired into the air to keep back a crowd at one petrol station, they said.
The army spokesman said violence broke out outside at least four petrol stations but he could not confirm that soldiers opened fire.
"We are taking measures to control the crowd," he told Reuters. "We are doing our best to bring about a normalisation of the situation."
Clerics appeal for calm
Shia Muslim clerics were at the main flashpoint, a petrol station at Saad Square, trying in vain to convince a crowd of hundreds to stop hurling stones at the troops, witnesses said.
The spokesman said British officers were in contact with local authorities to contain the situation.
Hundreds of people also marched to the headquarters of the British forces - once a palace for the deposed Saddam Hussein - where they demanded the restoration of power and petrol supplies, witnesses said.
Stones were thrown at the guards.
About 10,000 British soldiers have been policing large swathes of southern Iraq since the US-British invasion in March forced Saddam into hiding and destroyed his government.