Team staff and stunned security guards twice had to enter the field to stop fights triggered by repeated scuffling between Lebanon's Zakaria Charara and Thai defender Suree Sukha during the hosts' 2-1 win in Phuket.
With 14 minutes remaining, in an apparent case of mistaken identity, Charara struck Surat Sukha in the head in retaliation for his twin brother Suree's earlier foul.
After the ensuing brawl, Lebanon stormed off the field in protest and were told to remain on the sidelines by incensed coach Emile Rustom, who had to be talked into resuming the match by Thai soccer president Worawi Makudi.
Five minutes later, Suree escaped a booking by the Thai referee after another vicious tackle on Charara, who started another melee by slapping Suree and captain Datsakorn Thonglao in the face.
Lebanon again left the field in protest but returned five minutes later, only for the embattled referee to blow the final whistle prematurely to prevent further brawling.
Former European champions Denmark beat North Korea 1-0 in the other match and meet Thailand in Friday's final.
