Iran's military says U.S. helicopters have been flying too close to its border with Iraq and may even have crossed the frontier, AP reported.
The statement, carried by the state news agency Wednesday, says the helicopters were seen in Iraq and are "likely to violate Iranian airspace".
The Iranian military said it would respond to any violation of its borders and warned the U.S. military to keep its distance.
The U.S. military has over 150,000 troops in Iraq who make extensive use of helicopters to transport forces and carry out patrols.
Iraq-based U.S. forces carried out a raid on neighboring Syria on Oct. 26, killing eight people.