BAGHDAD, Aug 25 (Reuters) - Al Qaeda leader Ayman al-Zawahri has called on Iraq's Sunnis to prepare for a "long guerrilla" war if Islamic State is defeated, according to a video seen on Thursday.

"The Sunnis of Iraq should not just surrender upon the fall of (their) cities into the hand of the Shi'ite Safavid army,'' he said in a video recording distributed by supporters, using a derogatory term for the army of Iraq's Shi'ite-led government.

"Rather they should reorganize themselves in a long guerrilla war in order to defeat the new Crusader-Safavid occupation of their areas as they defeated them before."

The Iraqi army is supported by both a U.S-led coalition and Iran in its fight with Islamic State, which seized much of northern and western Iraq in 2014.

(Reporting by Maher Chmaytelli and Stephen Kalin in Baghdad and Mostafa Hashem in Cairo; Editing by Dominic Evans) ((maher.chmaytelli@thomsonreuters.com; +9647901917030;))