A 48-year-old man was treated in hospital for a facial injury following the attack at the Allison Arms in Pollokshaws Road in the Pollokshields area of Glasgow.
Police said people in the pub were shocked by the level of violence involved in the incident, which happened at around 9.30pm on Saturday May 21.
Officers believe the men in the picture may be able to help with their inquiries.
The first man is described as white, in his 20s and of large build with short dark hair. He was wearing a red T-shirt at the time of the incident.
The second man is white, in his 50s, with dark hair, and was wearing a blue polo shirt under a dark jacket.
Detective Constable Paul MacDonald, the officer leading the investigation, said: “This incident has left a man seriously injured.
“Those drinking within the pub were also shocked at the level of violence displayed that evening. It is crucial we trace those responsible.
“We are appealing for anyone with information or for anyone who may recognise the men in the image to contact officers at Cathcart police office on 101.”
Crimestoppers can also be contacted anonymously on 0800 555 111.