Iran has warned U.S. forces in Iraq that it will "forcefully" respond to any violation of Iranian airspace.
Iranian state media relayed a statement Wednesday from the armed forces saying U.S. helicopters have been seen flying close to the Iran-Iraq border.
The statement says the aircraft's proximity to the border creates the danger of a violation of Iran's airspace.
The warning came after U.S. forces attacked Syria last month in a cross-border air raid from Iraq, that Syria's government says killed eight civilians.
It also follows the election of Barack Obama as the next president of the United States. Mr. Obama has said he will engage in dialogue with Iranian leaders.
The Reuters news agency quotes an Iranian politician as saying the warning is a clear message to the president-elect. The politician, who asked not to be identified, said Iranian "radicals are not very happy" with the Obama victory.
The Iranian government has discouraged dialogue with the United States, and has arrested several academics who have advocated engagement between the two countries.
Iranian government spokesman Gholamhossein Elham on Wednesday said he hoped President-elect Obama would make fundamental changes in the approach of the U.S. towards global issues, and end aggression toward foreign countries.
And IRNA news agency quotes Iran's foreign minister, Manouchehr Mottaki, as saying the election of Barack Obama is a clear sign of the American people's wish and desire for fundamental changes in America's domestic and foreign policies.
Some information for this report was provided by AFP and Reuters.