The incident happened around 3:45pm after the female victim got off the bus on Portsmouth Road near the junction of Station Road.
She walked towards the Marquis of Granby pub when the suspect approached grabbed her shoulders and tried to push her to the ground.
The suspect told the victim he was in his early 20s, from Japan, and he’s described as 5ft 9, of slim build and wore a yellow jumper.
Any witnesses are urged to contact police on 101.