Three goals in the first period from Mohammad Mokhtari, Hamid Behzadpour and Reza Amiri seemingly sent the contest in Iran's favor.
Argentina fought on, though, and twice brought the score to within one, but Iran turned on the power to score through Mohammad Moradi, Movahed Mohammadpour and Ali Mirshekari to send the South Americans home.
Iran, third in the 2017 edition, will face Tahiti on Monday needing a win to top Group B.