Four crew and eight passengers were listed as being on board the UH-60 Black Hawk which crashed on Saturday, the US military said on Sunday, adding that it was being investigated.
The helicopter went down in a sparsely populated area 12km east of the town of Tal Afar shortly before midnight on Saturday. It had been flying between bases in northern Iraq when communications were lost with the aircraft, the statement said.
An immediate search and rescue operation was launched from nearby military installations and it was found at midday on Sunday.
In Falluja, 65km west of Baghdad, three marines were killed by small arms attacks on Sunday.
On Saturday, two marines were killed by roadside bombs in separate incidents, the military said, one near Karmah, 80km west of Baghdad, and another near Ferris, about 60km north of Baghdad.
In other violence on Sunday, a fighter was killed when clashes broke out between attackers and Iraqi police, Major Musa Abd al-Karim said.
Armed men also opened fire on a vehicle in Baghdad, killing the driver, police Captain Qasim Hussain said.
And employees at Falluja general hospital said they were going on a three-day strike in protest over the killing of a doctor shot by armed men on Friday, said Dr Abdullah Hussain, the hospital director.