At least 18 attackers, five US soldiers and a civilian travelling with the troops were wounded during Sunday's ambushes.
"The fourth infantry division repelled multiple ambush attacks," Lieutenant Colonel William MacDonald told reporters.
"The attacks were coordinated in locations very close to each other," he said, adding that the ambushes were made on separate US convoys using mortars, grenades and small arms fire. Three buildings, from whose roofs the attackers fired, were destroyed.
Some of the attackers wore the attire of Fidayin, a militia formed by Iraqi leader Saddam Hussein before US-led forces toppled him earlier this year.
The Fidayin are among the former regime loyalists whom Washington has blamed for rising resistance against the US occupation of Iraq.
"This is the largest (ambush) for our task force since we've been in the area," MacDonald said.
He declined to say whether the coordinated ambushes were linked to attacks on civilian foreign nationals in the Tikrit-Samarra area in the last two days.
Samarra and Tikrit, where the 4th infantry division is based, are located in the centre of Iraq where most attacks on foreign forces and Iraqis cooperating with them have been concentrated.