The man, aged 24, was assaulted outside The Thomas Botfield Wetherspoons on a Saturda night in August, West Mercia Police said.
The incident happened at about 10.30pm on August 22 outside the pub in Central Square.
Officers have now released CCTV images of men believed to be in the area at the time, who they say may be able to help with investigations.
The victim suffered minor injuries.
Anyone with information should contact West Mercia Police on 101 or online at westmercia.police.uk, quoting incident reference number 22/71369/20.
Alternatively, contact Crimestoppers anonymously on 0800555111 or crimestoppers-uk.org.