A man was hospitalised after being assaulted in a Culmore restaurant in the early hours of Sunday, January 10.
Detectives are investigating the assault in Pitchers Restaurant in the Alder Road area.
It was reported that a man, aged in his 30s, was assaulted by another man.
He was taken to hospital for treatment for a head injury.
A 34 year old man was arrested on suspicion of causing grievous bodily harm with intent.
Detectives are appealing for anyone who witnessed the incident or anyone who has any information that can assist with the investigation to contact them at Strand Road Police Station on the non-emergency number 101.
Or, if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.