The hosts lost 2-3 to powerful Korea rivals in the last match of the round robin format tournament.
Lee Kyudong opened the score in the 54th minute with a strong header in the box.
Cai Van Quy of Vietnam netted twice in the 74th and 77th minutes both from counter-attacks.
Park Janghangyeol levelled the score with a successful penalty in the 85th just three minutes before captain Kim Raewoo made it 3-2 from a close-range finish.
The Republic of Korea won all three matches at the four-side tournament and grabbed the gold medal. Vietnam came second with two wins and one loss.
Earlier, Russia beat Myanmar 3-1 to take the third position at the tournament.-VNA/VNP
