The incident happened on Thursday, May 29th at around 4pm at Garbí station, on line four of Valencia's metro.
A video of the attack shows two uniformed security guards hitting the young man with batons, while fellow passengers scream and shout at the men to stop.
The security guards claim the man did not have a ticket and was wearing his trousers too low, according to Spanish daily, 20 minutos. When the passenger was told to pull them up, he told the guards he could wear them how he liked, witnesses reported.
According to Valencia's tram authority, FGV, the young man entered the train with his trousers down and without carrying a ticket. The two security guards have since filed a complaint that they received injuries in the scuffle with the passenger.
FGV sources also apologized for the actions of the security guards, condemning the force used by the men, who are employees of security company Garda.
The company has opened an investigation into the incident and has requested the cooperation of Valencian police.
The two security guards have been suspended from duty on request of the FGV pending the outcome of the investigation.