The U.S. military says it has detained five people in the northern Iraqi city of Irbil suspected of links to activities targeting Iraqi and U.S. forces.
The regional Kurdish government of northern Iraq says the raid early Thursday was on the Iranian consulate. Iran also condemned the raid as being against diplomatic norms and asked Iraq to secure the release of its nationals.
But the U.S. Defense Department denies the raid was on a consulate. It said appropriate action would be taken against those detained once an investigation is complete.
The United States accuses Iran of providing material support to the insurgents, and allowing terrorists to use Iranian territory to cross in and out of Iraq.
Last month, American forces in Baghdad detained several Iranians suspected of planning attacks against troops in Iraq.
Separately, the U.S. military said coalition forces killed eight suspected terrorists and detained seven others in raids in the Tarmiyah area, north of Baghdad.