China led 16-14 in the third set, before Iran rallied after a time-out, pushing the game into extra points before a Chinese error handed them victory.
The Chinese women are also on their way to Tokyo after beating Japan in their final in Bangkok, also in straight sets – 25-16, 25-4, 25-7.
Like Iran in the men's competition, China were dominant as they won the title without dropping a set.
Japan led during the first set, before China found their rhythm and swept to a very comfortable victory.