The incident happened at 3.56 am Saturday 13 July at Pizza Express on St Sampson's Square.
Please get in touch if you recognise the person in the image as he could have information that will help the investigation.
Please email Ben.Hutchinson@northyorkshire.police.uk or you can call North Yorkshire Police on 101.
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111 or via their website.
Please quote reference 12240124279 when passing on information.
York appeal after man assaulted outside nightclub
North Yorkshire Police are appealing for information after a man was punched to the back of his head on Rougier Street in York.
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