Hassan Ameen gave Al Wahda the lead after 54 minutes, but they were pegged back 12 minutes later when Hossein Badamki equalised for the Iranian hosts.
The result means Al Wahda remain unbeaten, with two draws so far, while Piroozi are off the mark with their first point in Group C.
After a minute’s silence to respect the victims of the earthquake and tsunami which have caused devastation in Japan, it was Piroozi who began to dominate possession.
They had their first chance in the 15th minute when Gholam Reza Rezaei's cross was met by Hadi Noroozi's close-range header but goalkeeper Ali Al Hosani was alert and prevented the goal.
Al Wahda’s Brazilian striker Hugo threatened at the other end nine minutes later when he collected a pass near the edge of the penalty area and struck a shot which took a deflection and was gathered by Rahman Ahmadi.
Basheer Saeed then took aim at goal from long range but was denied by the Piroozi goalkeeper.
Alireza Nourmohammadi almost broke through for Piroozi a minute before half-time, but his powerful header from Gholam Reza Rezaei’s free-kick was comfortably saved by Al Hosani.
Hugo went close with a header early in the second half for Al Wahda, and they went ahead soon afterwards when Ameen received a pass inside the penalty area and produced a superb finish, finding the top corner beyond the reach of Ahmadi.
Al Wahda almost doubled their lead four minutes later when Ismail Matar met a long kick forward from Al Hosani but fired wide.
Piroozi pressed for a leveller but almost conceded when Nourmohammadi passed to Mohamed Saeed Rashed rather than a team-mate but there was no punishment.
The equaliser came when Hadi Noroozi fed the ball to Mohammad Nouri and he picked out unmarked midfielder Hossein Badamaki to score.
Piroozi began to look the more dangerous side and Noroozi sent a shot wide, while Mazyar Zareh also failed to find his range from the edge of the penalty area.
Nourmohammadi might have pinched victory for Piroozi late on when he received a pass with his back to goal but managed to get in a shot which Al Hosani proved equal to.