Russian Roman Murashko scored 25 points and Bardia Saadat led Iran with 22 points.
The defending champion will face Bulgaria in the classification 5-8 on Thursday.
The 2019 FIVB Volleyball Boys' U-19 World Championship is the sixteenth edition of the FIVB Volleyball Boys' U-19 World Championship, contested by the men's national teams under the age of 19 of the members of the Fédération Internationale de Volleyball (FIVB), the sport's global governing body.
The tournament is being held in Tunisia from August 21 to 30.