The Iranian government says it has decided to suspend talks with the United States until the American forces end their current assault against Shiite militias in Iraq.
Iran and the United States have held three rounds of ambassador-level talks on security in Iraq since last May.
Washington has accused Tehran of supporting Shiites in Iraq.
But Iran has blamed violence in the war-torn country on the US presence.
Iraq's government spokesman, Ali al-Dabbagh, said the crackdown would continue even if Iran pulled out of the talks entirely.
The spokesman said his country does not want trouble with Iran, and would not be pushed to take an aggressive attitude toward the country.