Police Inspector Jivba Dalvi said the group thrashed four persons, including the manager and a room boy of the guest house, over some petty issue.
Two injured persons were admitted in the Goa Medical College and Hospital in serious condition, he said.
Police have arrested all the 15 tourists and booked them under various sections of the IPC, including attempt to murder.
"We have also attached one mini bus bearing Telanagana number plate which was used by the accused persons," he said.