The 56-year-old coach has replaced Slovenian coach Borut Macek in Team Melli.
Kastratovic is a Montenegrin-Macedonian handball coach. His wife is Macedonian well-known handball player Indira Kastratovic.
He has already coached Macedonian team RK Vardar and El Jaish of Qatar.
Kastratovic will lead Iran national handball team in the 2018 Asian Games in Indonesia.