The holidaymaker was found early on Wednesday morning "in a state of semi-consciousness" by a man walking on Miramare beach, Corriere reported.
She was taken to hospital, where doctors found injuries conducive to rape, the newspaper said.
The latest alleged attack has sparked alarm in Rimini, which is popular for its beaches and nightlife.
Authorities are now considering despatching plain-clothed police officers to patrol its beaches.
The potential move also comes after a 20-year-old from Milan was allegedly raped on the same beach on the Ferragosto holiday last weekend. The attackers fled after the girl's screams attracted passersby.
In another case, a man attempted to rape a 24-year-old from Rimini, but she managed to escape.