Black mailing is not allowed in Islam. Asking money from people must be based on lawful contract i.e. selling , renting, etc. As he did not commit the crime, you can not ask him for money just for trying to harm you. Such money will be illegal money.
If he hit you causing reddishness on your body or more effect, then you will be entitled to take penalty ( Diyyah) from him. The penalty amount depends on the extend of the harm on your body caused directly by him.