Iran's foreign minister says the nuclear deal reached last year with world powers can't be renegotiated despite Republican presidential contender Donald Trump's pledge to do so if elected.

After a lecture in Stockholm, Mohammad Javad Zarif said the deal "is not an Iran-U.S. agreement for the Republican front-runner or anybody else to renegotiate. It's an international understanding annexed to a Security Council resolution."

Trump has denounced the deal and said he'd seek to renegotiate it if elected president.

Zarif also criticized Saudi Arabian Foreign Minister Adel al-Jubeir for calling on Iran to stop intervening in Iraq, saying "we will leave Iraq whenever Iraq asks us to leave."

Iran says its military advisers in Iraq are there at Baghdad's request to help Iraqi forces fight Islamic State militants.