This is unexpectable and you should voice up. Either you handle this personally or you should defend yourself publicly. If you are thinking of handling this situation personally, cross-check that you will be safe if you defend yourself. Your security is important and if you take this in public then it would be much better as you will get supported by people around you. Raise your voice against this activity and protect yourself. Involve your family in the matter and ask them to help you or file a case against the policeman.