Police are investigating an assault and robbery at a fast food outlet in Malvern East last month.
Investigators have been told four males were sitting inside eating about 4.15pm on 13 October.
They were approached by several unknown males who made demands for jewellery, money, mobile phones and clothing.
The victims refused and two of them were punched before a mobile phone and a credit card was stolen.
The offenders left the Dandenong Road store on foot.
Investigators have released images of three males they believe may be able to assist with their enquiries.
Investigators are urging anyone with information or who witnessed the incident to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au