neighbor problem, any advises will help !?

Talk to your neighbors about it first. They may not know you don't like it. Let them know you understand that kids have played there before you moved in. Even so, you would like them to play in their own yard. If they're good neighbors they will respect this. I would even say to the ones who told blamed you, you are not responsible for their children playing on your property. If the parents don't listen and their children still trespass, give them one last warning. Tell them firmly, you are not their children's babysitter. You don't want them on your property. You pay for that property and have every right to keep them off. Tell them you don't want to bring it to the authorities, but you will if you have to. Any damages done to your property by their children they will be responsible for. If they call you a child hater, so what? They probably don't want to have to deal with their kids so they send them elsewhere. Don't let your neighbors walk all over you because you're the new guy.

The previous owners probably had children of that age and welcomed them there. I would suggest that you tactfully tell some of the neighbors that you work nights and the playground atmosphere is keeping you awake during the day. You would rather that they didn't play in your yard. If this does not work, you might consider fencing the yard.

Speak to your neighbors,if it does not work consult an attorney. They are trespassing.