It occurred at around 2.20am on Saturday 21 July 2012, on George Hudson Street, outside Reflex.
The suspect followed a 20-year-old local man out of the club before allegedly punching him in the face. As a result of the assault the victim had a tooth knocked out.
Shortly after the assault, someone is seen to pick something up from the floor and follow the victim.
PC Nicola Elliot, of York Safer Neighbourhood Team, said:
If you witnessed the assault or can help to identify the man caught on CCTV please contact the police or Crimestoppers straight away.
I am particularly keen to speak with the person caught on camera shortly after the assault as I believe they may have vital information that could help me with this investigation.
Anyone who can help the police with their enquiries is asked to contact York police on 101, press option 2 and ask for Nicola Elliot. Alternatively information can be emailed to Nicola.firstname.lastname@example.org
Or call Crimestoppers anonymously on 0800 555 111 quoting reference number 12120118252.