Police are searching for a man who may have information about an assault in inner-Sydney last month.

On February 27 about 9.15pm, a man was sitting with a friend in a restaurant on Thomas Street in Haymarket.

The 23-year-old was approached by another man from behind, who struck him in the back of the head with a glass bottle and spectacles and threw them back into his face, NSW Police said.

NSW Police have released CCTV after a glassing in Haymarket. (NSW Police)

The injured man was taken to St Vincent's Hospital where he required 14 stitches to close a head injury.

Today police released CCTV of a man who may be able to assist with the investigation.

He has been described as being of Asian appearance, about 175cm to 180cm tall, of a medium build, aged in his 30s, and with black short hair.

The man is depicted in the vision wearing a black shirt and black pants.

Sydney City Police Area Command Crime Manager, Detective Inspector David El-Badawi, urged the public to look closely the vision.

They want to speak to this man in relation to the assault. (NSW Police)

"Our detectives are very keen to speak with this man or anyone who can help us with this investigation," Det. Insp. El-Badawi said.

"From all accounts, this was an unprovoked and cowardly assault and an action that we will simply not tolerate.