I'm thinking of beating up the man.
Why are you considering beating a man up?
He provoked me by showing his sexual activity
You should report harmful and illegal sexual activites to the police. Instead of physically hurting someone and risking your own life and safety, you should talk to the person about what they have done and why it was unacceptable.
So, I should make a police report?
Yes, you must tell the police immediately in case he is doing this to other people. His actions are very harmful to not only you, but to others.