Shock horror! Young people hanging around the pub on a Saturday night. And even more shocking they might be experimenting with some interesting cigarettes.

So what?

Is there any actual (and just not perceived) threatening and abusive behaviour? What evidence do you have that that it's not safe to go out. Are there any crimes being committed (apart from the relatively minor smoking)? If there are crimes, call the police.

Otherwise just ignore them, they probably aren't doing anyone any harm.