Are you serious about this advice? Parents cannot be politely approached by a neighbor, because their kids, who they chose to have, are disturbing others regularly?
Yeah, I mean, I didn't type it out longform, but step 1 is obviously to find out what's going on. There might be some very strong underlying cause for the behaviour that means it's going to be difficult or impossible to change... but you can't find that out if you don't talk to the parents. Knowledge promotes understanding, etc.