The two air strikes carried out by fighter jets include one near the Mosul Dam, and the other near the town of Amerli, home to thousands of Shia Turkomen minority people, Xinhua quoted a statement by US Army's Central Command as saying.
The residents of Amerli have been cut off from receiving food, water, and medical supplies for two months by the IS forces.
The strikes were conducted under authority to protect US personnel and facilities, support humanitarian efforts, and support Iraqi forces that are acting in furtherance of these objectives, the statement said.
The US Central Command has conducted a total of 120 air strikes across Iraq.
On Sunday, Iraqi security forces broke through Amerli after three days of fierce clashes aimed at ending the two months long siege by IS militants.
The US president first authorised limited air strikes on IS targets Aug 7, as the group seized more cities and towns in its advance on Erbil, capital of Iraq's autonomous Kurdish region, and trapped many civilians including the minority Yazidis on Mount Sinjar.