Justin' Bieber punches fan in Barca

Justin Bieber has been caught on camera punching a male fan through the window of his chauffeured driven car while arriving for a concert in Barcelona. The man who was left with a split and bloodied lip after the encounter was visibly upset.
There's no sound on the video so what transpired in that brief moment is not for certain. However  the man could be seen dipping his hand through the car's window before he got punched. Was bieber trying to protect himself? Was the man an annoying paparazi?
Nice jab justin.