The 19-year-old Bieber was charged by a partier at a Toronto nightclub (http://www.usmagazine.com/celebrity-news/news/justin-bieber-attacked-at-toronto-nightclub-report-2013318) where he was performing Friday night. The attack happened as Bieber stepped off stage to get closer to some of the regular people.
The attacker rushed at the singer and started pulling on his shirt. Bieber was seen trying to defend himself, kicking at the attacker, before security pulled the attacker away and tackled the attacker to the floor.
[youtube]http://www.youtube.com/watch?v=dIVlkUHQjRA&sns=em[/youtube]
"Justin defends himself against shirt-puller" EH.