Abel Ruiz (13th minute) and Sergio Gomez (60th) gave Spain a decisive advantage before Ferran Torres (67th), who had a hand in both goals, found the target himself.
Saeid Karimi (69th) scored the only goal for Iran.
Spain will meet African U-17 champions Mali in the semi-finals.
Torres was in excellent form for Spain down the right wing and his combination with centre forward Ruiz created all sorts of problems for the Iran defenders.
Iran goalkeeper Ali Gholam Zadeh denied Spain a sure goal when he came off his line to successfully beat Ruiz to a cross from the right and punch the ball away. Mateu Jaume's attempt off the rebound from outside the box hit the side netting.
Spain however, did not have to wait long for their first goal as Ruiz found himself in possession inside the Iran penalty box only a couple of minutes later.
Although the Spain centre forward's first shot was blocked by Iran's Amir Esmail Zadeh, his first time attempt off the rebound found the net.
It was Torres who had started the move, beating the Iranian left back to put in a cross into the penalty box.
Spain nearly doubled their advantage soon after, but Gholam Zadeh made another superb save to deny Cesar Gelabert at his feet, with the ball flying over the Iran crossbar.
Gomez ended Iran's chances of making a comeback on the hour mark when he picked up a pass from Torres before turning and beating Gholam Zadeh with a superb strike from outside the box off his left foot.
Torres compounded Iran's misery when he made an excellent run from the midfield before finishing off Mohamed Moukliss's low cross with a diving attempt.
Iran pulled a goal back when Allahyar Sayyad's header off a long cross went towards Karimi who rose high above the Spanish defence to head the ball in.
Sayyad created another superb chance for Iran in the 83rd minute, but Karimi's diving effort off the pass went inches wide.
Spain however, held on to secure their spot in the last four stage.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
About VDC
Doraiah Chowdary Vundavally is a Software engineer at VTech . He is the news editor of SocialNews.XYZ and Freelance writer-contributes Telugu and English Columns on Films, Politics, and Gossips. He is the primary contributor for South Cinema Section of SocialNews.XYZ. His mission is to help to develop SocialNews.XYZ into a News website that has no bias or judgement towards any.