The Iranian team, who had defeated Italy and Mexico, swept China in straight sets (25-23, 25-18, 25-21) in Pool D.
Morteza Sharifi abd Pouria Yali each scored 14 points for Iran and Qi Qi scored eight points for the Chinese team.
Iran will meet Czech Republic on Tuesday.
The tournament is being hosted by Bahrain in the cities of Riffa and Isa Town from 18 to 27 August 2017.
Host Bahrain is in Pool A, with the USA, Puerto Rico, Egypt and Tunisia. Pool B consists of Poland, Brazil, Cuba, Japan and France. Argentina, silver medalist in 2015 has been drawn in Pool C, along with Russia, China, Korea and Turkey. Pool D features Iran, European heavyweight Italy, Mexico, China and the Czech Republic.