Guernsey Police is appealing for witnesses to the incident, which happened some time around 19:20 on Friday 31 July.
Officers would like to speak to a female described as being in her late twenties/early thirties, wearing sportswear and walking three Yorkshire Terriers.
Police would also like to speak to anyone else in the area at the time of the alleged assault.
Anyone with information is asked to contact PC 90 Robinson on 725111, or call Crimestoppers anonymously on 0800 555 111.