A police detective and his prosecutor girlfriend are suing the city and the NYPD for $10 million, claiming they were roughed up and wrongfully arrested last year, Brooklyn federal court papers show.

Detective Samir Gonsalves — who admitted to riding with the motorcycle gang that beat a Manhattan motorist last year — claims he was knocked down by officers who confronted him with his girlfriend, Queens Assistant DA Jacqueline Rizk, on Aug. 3, 2013.

An officer then threw Rizk up against a car, court papers state.

The couple was charged with resisting arrest. Cops said they were initially called to the scene because the pair was fighting.