Other kids

Whenever your child encounters other children there is a certain amount of suspense, and danger.  Will the other kids play too rough with your child?  Will your child be the one who is more aggressive than is socially acceptable?   Kids are not the best at thinking before they act.  And even without meaning any harm some one could get hurt.  Especially when there is an age gap, or a height/weight difference.

Bigger kids running around might bump into smaller ones inadvertently causing tears.  Little one might latch on to an item that isn't theirs and become unwilling to part with a thing they have never seen before.  Again there is drama!

And all of this contention can happen without the kids in question feeling mischievous.

What do you do when your child aims to misbehave with their peers?

A firm warning might not be enough, you may have to remove you child from the situation.  People are not born with an innate understanding of the social contract.  As a parent it is you job not only to teach them how to play nice with the other kids but to also impart the importance of behaving in a socially acceptable manner.  If you don't you will find yourself invited to fewer and fewer social gatherings because no one wants to deal with a child who is being a holy terror.

What do you do when the other kids are being the problem?

I recommend starting by asking their parents to intervene. (If you know who / where they are)  People can be touchy about other adults interacting with their child regardless of intent.  That said feel free to rescue your child.  You may or may not have the means to eject a problem child, but you can change where you and your child are.

If your child has witnesses other kids setting a bad example it might be good to have a gentle talk with your child and explain why what the other kid did was wrong and why they should not attempt to duplicate the behavior.  That said, keep your calm, your child is not in trouble for what someone else did and you should go out of your way to make it clear you are not mad at your child but you do need to explain the rules.  Also check in with your child, were they bothered, scared, or hurt by what happened?  How do they feel about seeing someone else breaking rules and possibly even getting away with it?