The incident happened in Acomb at about 4.50pm on Friday (22 May 2015).
The man, in his 20s, was walking along a cycle path leading from Danebury Drive towards the Morrisons supermarket.
He was approached by two unknown men on bicycles who punched him to the floor, searched his trouser pockets and attempted to steal his bag.
The victim was then kicked in his ribs and head resulting in hospital treatment, including stitches to his face.
The suspects made off empty-handed towards Woodlea Avenue after the victim shouted “Police”.
The victim remembers seeing a man walking a dog at the time of the robbery.
Police are appealing to the dog walker to come forward who may not have realised what was happening.
One of the suspects was riding a red and white mountain bike and is described as white, aged between 20 and 30, and was wearing a black baseball cap and black hooded top.
Anyone with information that could assist the investigation is urged to call DC Kevin Goodman from the York Serious Crime Team on 01904 669453.
Or call Crimestoppers anonymously on 0800 555 111.
Please quote reference number 12150084770 when providing information about this incident.