Its tough for us as Claire's Autism prevents her from understanding social cues/behaviours. Unfortunately, I've had to tell her that she can't play with certain kids because they're just downright mean to her.
She doesn't see it, bless her heart. But I do, and it very much bothers me. And until she can learn the social cues when someone either doesn't want to play with her or the behaviours they're doing aren't nice then personally I feel I have to intervene.
She's had kids be physically violent with her, and she still doesn't pick it up.
I don't believe in picking a kid apart though. You never know what's going on behind closed doors. But I do tell her that sometimes people's personalities clash and that doesn't make anyone bad/mean... just means you find friends who you mesh with better.
(In kiddo terms, of course. And as much as she can understand that with her Autism).