Luas operator Transdev has confirmed it's investigating an incident which happened at the Bluebell Luas stop on Friday.
In a video shared to social media, a uniformed ticket inspector can be seen restraining a young man.
Local Sinn Féin Councillor Daithí Doolan has seen the video and said the incident was unacceptable shocking.
"I don't know what was in the lead-up, I don't know what the context is but what I have seen is quite a shocking level of violence being used."
"We need to ensure that anybody who is patrolling or policing the Luas is of a certain standard and that they don't use brute force against any passenger because it is terrifying. If I was on the Luas and I saw that, I'd be terrified."
