The incident took place on Howard Street at its junction with Stockwell Street around 11pm on Friday, December 17, when a 36-year-old man was assaulted.
The victim was taken by taxi to Glasgow Royal Infirmary for treatment for facial injuries.
Detective Constable David Copeland, of Stewart Street CID, said: “We are appealing to anyone who who was in the area around the time of the incident and may have any information or dash cam footage to get in touch.
“I am particularly keen to speak to the driver of the black hackney taxi who drove the victim to Glasgow Royal Infirmary.
“If you believe you can assist our investigation, please call 101, quoting incident 1995 of 22 December. Alternatively, you can contact Crimestoppers on 0800 555 111, if you wish to remain anonymous.”