How can I refuse to fight and let me help?

Fighting is illegal, and breaking the other side is a crime. It's a very good idea that you don't go when others ask you to help. But I don't want to hurt anyone. You can persuade him to explain the harm and serious consequences of fighting. It can also show that your parents are very strict in discipline, and what will happen if your parents know. Finally, it can be directly explained that the help of friends is good help, not bad help. The era of "doing anything for a friend" is an era of ignorance. If you lose this friend because you don't help fight, it means he has a problem, and losing such a friend is not necessarily a bad thing.