The incident happened in The Pit at around 1.30am on Friday, April 21.
North Yorkshire Police today said that the incident had involved a large group of people being asked to leave the premises in The Ginnel.
A spokesman said: "One man, pictured in the CCTV images, remained in the bar and is believed to have directed abusive and insulting words towards the victim.
"Officers are appealing for anyone who can help us to identify the man to get in touch as he may have important information that could assist our investigation."
Anyone with any information is asked to email [email protected] or call 101, select option 2 and ask for Neil Roworth.
Information can also be passed on to Crimestoppers on 0800 555 111.
Please quote reference number 12170069125 when passing on information.