Maybe there is a reason that he is unable to explain as to why he only gets aggressive around them as he is too young. You can always try telling your child, that you understand that they must be upset or disappointed about the other kids or probably they make him feel that way. You can try doing a role play at home with him during play time and name yourself and the other parent as the name of the kids he hits. See what is his response and ask him what should you do, how does he want you to play (as the other kid). Avoid blaming the child always and making him feel bad about it, probably that is not working with him.

Hi, I understand that you are worried about the way your son behaves with his friends. You are wondering what is causing your son to behave in a certain way with friends who are around his age while he enjoys the company of other people. You can consult with a psychologist and explain about your son’s behaviour. There could be reasons why young children behave in a certain way. You can explain about your son’s behaviour in detail to a psychologist.

Hi, maybe your child is feeling too comfortable with them to be himself or he is annoyed looking at you treat the other kids :) There are quite a few possibilities and this requires a lot more details and consistent parenting style. I suggest you take a counseling session with one of the psychologists and get an opinion.