Yo K
I've had that happen more than once. Actually it really doesn't bother me that much unless your friends catch you trying it [In a public place/club, etc]. Then they never stop antagonizing you.
If it is in a public place or something I just shrug it off and continue to have a good time etc. Act like nothing happened. If you are one on one and try it and she backs away, the big key to try and not feel embarrassed. You showed your manly balls by making an advance on her and showing your feelings. You proved to her that you don't want to be in the friends zone with her and now she knows it.
Don't be ashamed of it, maybe she just isn't ready yet, or maybe its a test.
Usually if I really feel that she wants me to kiss her but then she backs down, I usually go for it again a little later on. A lot of times they will break down the second time. It may almost be a defense mechanism on their part.