Masjedi finished in the first place, throwing 8.73 meters in the Men's Shot Put-F53.
Alireza Mokhtari, also from Iran, won the silver with 8.59 meters.
Alaa Abdulsalam of Syria seized the bronze with 7.87 meters.
As the Asian Para Games returns to China for the second time following Guangzhou in 2010, nearly 3,100 athletes from 44 countries and regions are taking part across 22 sports and 564 events at the Hangzhou Asian Para Games, which runs through Oct 28.