I am with my girlfriend since eight months. Actually, we are engaged. We went out together to the seashore, and when we were in romantic moments, I made my move and kissed her. I saw that she wants more than I went deep. But after two days, she mailed me saying that she didn't like what happened between us and she hate remembering it.she said that she never imagine that I could do that for her. She said as well that she was trusting me n she didn't want me to kiss her but she couldn't escape.

So, my question is: does she really regret to had that kiss or does she simply want to say something else?

You are engaged and she hated kissing you? Boy, you're in trouble.
Ask her what she didn't like about it.

You better ask her what wrong with kissing the guy you are engaged to. Then forget her. That's a bad sign when a female hates kissing you and makes such a big deal of it.

This has to be a blessing in disguise.

What are your ages and previous relationship experiences? This sounds almost virginal. Not trying to be smart here or anything. If there is a deep spiritual commitment to God in her it will explain a whole lot. People have a tendency to forget that a commitment to God overrides all other commitments. If she is deeply spiritual she may have felt that you were trying to cross a physical line that cannot be crossed before marriage in her eyes.
If there is something other than that - you may want to ask her if she is wearing that engagement for the wrong reasons. I do not know what your relationship is like - but if you are "spoiling" her with gifts - back off for a while and see how she acts.