What should I do if someone is blackmailing me for money?

My bike was hit by another bike. The other rider fell and got some minor injuries, but I was unharmed. I asked him if he needed medical help, but he said his father is in the police and will pay for the damage to his bike. I offered insurance, but he refused. Now, he is blackmailing me, demanding money or threatening to file a false case against me with his father’s help. He got his bike repaired, even though it wasn’t damaged in the accident. I offered him some money, but he is not agreeing. What should I do?