A woman was grabbed by a man as she walked along Montagu Street in Kettering.
The victim was walking towards the town centre when a man grabbed her arm from behind just after 5am on Saturday, September 26.
She shrugged him off and ran away.
The offender is described as a black man, aged between 30 and 40, about 6ft and wore a dark coloured hooded top with the hood over his head.
A police spokesman said the woman was not injured during the incident.
Anyone with any information can call Northamptonshire Police on 101 or they can call Crimestoppers anonymously on 0800 555111.