C.V.
You need to teach your daughter to place boundaries. Learning to place healthy boundaries in social situations is a skill that will help her for the rest of her life.
The book "Queen Bees and Wannabes" is an excellent resource for tween and teen girls when it comes to dealing with pushy girls and social circles. While it was really written for middleschoolers, I'd suggest checking it out from your local library and reading it. You'll find some good tools to help teach your daughter to set healthy boundaries, what social behavior is acceptable and what is not, and to work on her resiliency in accepting rejection from someone she really doesn't want to be around anyway.
Best of luck.
C. Lee