The match was held as part of the third week of the Volleyball Nations League (VNL) 2023 underway in the United States.
The Iranian team lost the game to its European rival while it was in the lead 2-1 at the end of the third set.
Bulgaria, however, made a comeback and won the next two sets to defeat Iran 3-2.
Iran is scheduled to hold its next match of the tournament against Argentina early on Sunday.
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