Mabkhout's low shot in the 59th minute beat Oman keeper Ali Al Habsi to decide the outcome after both teams bowed out in the semi-finals earlier in the week.
UAE lost 3-2 to hosts Saudi Arabia in the tournament's best game so far while Oman, the 2009 champions, squandered an early lead to lose 3-1 to Qatar. Saudi Arabia and Qatar will contest the final on Wednesday after they drew 1-1 on the opening day.
"Of course, this is not what we came here for. We came to be champions but the players did their best and I have to thank them," UAE coach Mahdi Ali told reporters. "Today we gave a chance to more players to see them ahead of the Asian Cup."
The Asian Cup takes place in Australia in January.
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(Editing by Ken Ferris)
