Officers from Prahan are investigating an assault which occurred outside a licensed venue in South Yarra earlier this year.
Investigators have been told a 22-year-old Irish national was in the company of two females when the group was approached by a man on Wilson Street about 3.30am on 16 February.
After a brief argument the unknown male attempted to punch the 22-year-old several times but the strikes were avoided.
The Irish national then offered a handshake in an effort to end the conflict but he was punched in the face by the unknown offender who then walked away from the scene.
The offender was perceived to be Caucasian, of solid build with a bald head.
Police are releasing vision of a man they believe could assist with their enquiries.
No arrests have been made at this stage and the investigation is ongoing.
Anyone with information that could assist police with their enquiries is urged to contact Crime Stoppers on 1800 333 000 or file a confidential report at