USA's Ben Patch scored 24 points while Amir Ghafour earned 12 points for the Iranian team at the Katowice Hall.
Iran will play host Poland Saturday night and face Russia on Sunday.
Iran still has a chance of qualifying for the Group 1 Finals.
The FIVB World League is the premier annual men's volleyball tournament with a total of 36 participating teams in 2017.
The 36 teams have been split into three groups of 12 teams and will play the preliminary round in a pool format over three weeks, before the best teams gather for the finals in each group.
