The Iranian team, who had lost to USA 3-1 at the Galen Center in Los Angeles on Sunday, was defeated against the defending champion 3-1 (25-15, 25-16, 20-25, 25-20).
Amir Ghafour led Iran volleyball team with 13 points and Matthew Anderson scored 19 points for USA.
The defeat left Team Melli at the bottom of Pool B without a point.
USA tops the pool with six points, followed by Russia and Poland with five and one points respectively.
USA had defeated Iran in straight sets in the 2014 semifinal in the FIVB World League.
Both teams also met in the first round of the 2014 World Championships when Iran proved too strong for the US in five sets.
USA participates in its 18th World League. They have won two gold, one silver and two bronze medals in their previous participations.
