Elham Anafjeh scored twice as her teammate Mahtab Banaei found the net once more, while Nastaran Moqimi scored an own goal.
Team Melli Banovan, who had defeated the Philippines 1-0 in its opening match, secured its place in the quarter-finals.
The win took Iran to six points –on a par with Vietnam who also qualified- as the two teams are going to meet on Sunday to decide the group winners.