Iranian parliament speaker Ali Larijani says more countries would be threatened by Islamic State terrorism if Iran did not help Iraq in its fight with the extremist group.
Larijani was speaking in Qatar on March 11, a day after talks in Kuwait.
Both countries are part of a bloc of Gulf Arab countries that recently accused Iran of interfering in neighboring Yemen, where a rebel Shi'ite group has overrun the capital.
U.S. Army General Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, said on March 11 that Iran is playing a helpful role against Islamic State militants in Iraq now, but once the extremists are defeated, Tehran-backed militias could undermine efforts to unify the country.
Earlier on March 11, Iraqi soldiers and Shi'ite militiamen entered Tikrit, Saddam Hussein's hometown, which is held by Islamic State.
Iranian military advisers were helping guide Iraqi forces in the advance.