Should you pay if you hit a parked car but he was not suppose to be parked there?

Well, the car didn't jump out in front of you. You are responsible for avoiding all objects. If it had been a kid standing there, would you have been responsible.?

To add to the above.

The status of the stationary vehicle doesn't really matter. If you hit it, then you are obliged to exchange details with the other driver. If you are unable to do, you should report it to the Police within 24 hours or it is considered a criminal offense.

"You" are entirely to blame and yes "you" should pay.