An Aljazeera corrspondent said the attacks occurred late on Monday.
In one attack, the US headquarters in Kafar Qassim and al-Qal’a camps were targeted.
In another, a US patrol was attacked in the city centre. In the third attack, a US tank in al-Hadi area of Samarra was ambushed. US soldiers vacated the tank immediately, the correspondent said, quoting eyewitnesses.
In northern Iraq, resistance fighters lobbed a grenade at Albanian troops, injuring at least one soldier and 13 Iraqis.
The attack took place on Monday afternoon outside a local authority building in the city of Mosul, spokeswoman Lieutenant Tate Noble said on Tuesday.
Details of the incident were sketchy, but the injured Iraqis were apparently bystanders.
Local hospital staff and witnesses said they believed one Iraqi may have been killed, and a total of three Albanians injured. They spoke of two grenade explosions and firing.
That could not be confirmed with the military.
"There were two US cars with soldiers in them. I heard the sound of shooting," Adison Butrus, one of the injured Iraqis, said from a hospital in Mosul.
"One grenade exploded. I ran away to nearby shops. When I went inside, another hand grenade exploded."
In the central Iraqi town of Baquba, US troops came under mortar fire on Monday in two attacks that triggered a fire, but left no immediate casualties, witnesses said on Tuesday.
"One grenade exploded. I ran away to nearby shops. When I went inside, another hand grenade exploded"
Muhammad Fayyad, a local farmer, said six mortar rounds were fired shortly before midnight at the old Ibn Fernass airport, housing US soldiers. He said a column of smoke rose from the site, but there were no estimates of damage.
The barracks were targeted by four more mortars shortly before dawn, he added.
Helicopters patrolled the skies above the location, northeast of Baquba for an hour and a half, in search of suspects but did not fire any shots, witnesses said.
The US military said it had no report of the attack.