If she loves you, she would ask you to talk to her when she has time. So you should wait some time, usually a couple of days.
Don't wait around for her. People who want to spend time with you will make an effort. It may be that she is just having a bad day, or is busy.
There are two possible reason with that kind of reaction. 1. She's having a bad day. Maybe she had a monthly period. 2. She wants to stay away from you. I can't really tell you the exact reason, but you may also consider that she's not ready to have a relationship with you. Give her space and time. I know it's impossible for you specially you're into her, but you don't have any other choice than to do it. Also, don't spoil her. She might take you for granted if she feels like you're always there for her.
Let it lie. Let her miss you a little. If and when she does, she will contact you. If she doesn't, then she's not the girl for you. You can't argue with a heart. You can only attract it or not.