The Luas operator Transdev has confirmed it is investigating an incident at the Bluebell stop on Friday.
A video posted on social media appears to show an altercation between two uniformed ticket inspectors and a young man.
The young man is seen reaching towards one of the ticket inspectors, who is then seen restraining the young man.
The young man falls to the ground, and the second ticket inspector holds him at the side of the platform.
The first ticket inspector is seen dropping his ticket book in the scuffle.
The two inspectors then keep the man on the ground, as one inspector appears to use his radio.
It is unclear if the young man involved was a disembarked passenger.
"This incident is under investigation. No further comment will be made at this time", Transdev says.
Local Sinn Féin councillor, Daithí Doolan has seen the video. He says training may need to be reviewed.
"I'm quite shocked, to be honest at what I've seen in the video.
"There seems to be an over-use of force on this passenger.
"I use the Luas on a daily basis, I have the height of respect for anybody who's working on the Luas.
"I think these people are well trained into dealing with these situations - I'm just wondering was the training put into operation."
"I don't know what the lead up is, I don't know what the context is - but what I've seen it's quite shocking the level of force used.
"And I would hope that the training levels are reviewed, updated, upgraded and are applied to all staff.
"We need to ensure that anybody who is paroling or policing the Luas is of a certain standard".
An Garda Síochána says it does not comment on material posted by third-parties.