Honestly, I wouldn't make it into a big deal. My normally very social & independent DD has had issues adjusting to K, too. She has cried, kicked & has not befriended as many kids as I thought she would. Once I stopped feeding into her "issues" & making a big deal out of everything, she improved 10 fold.
I look at it this way - do adults befriend everyone they work with, go to church with, or attend a mom's group with? Of course not. I know I don't like being forced to hang out with someone or being told who to be friends with.
It's part of life. Some people just gravitate towards each other, and some don't. Of course, as adults, we know how to be nice about this, and that this is a fact of life. Seeing your little one go through it is hard, trust me, I know. But it's a part of going to school, being a kid, and is an important life lesson.
I guarantee you she doesn't hate school, and I'm sure it will all work itself out. It takes some time to adjust when your whole little world has been turned upside down. My advice is to stay positive & teach your child how to cope when kids are less than nice to her, because the truth of the matter is that it will happen again. I tell DD that if someone messes with her, she is to ask them to stop, or go play with someone else. If the kid still bothers her, she is to tell a teacher/person in charge. Don't feed into the negativity, instead, focus on the good.