I met a girl in my university and she's my course mate too. After chatting for few days we decided to study and have lunch for the following week. It started quite well at the beginning and we texted each other for almost 1 week and she says she wants to know more about me, and we also plan to go for a walk, dinner, all kinds of stuff.

But something bad happened. I’ll get jealous whenever I see her with a boy or going somewhere else. And I kept like texting her not to go here and there and I’m just her friend only.

So she sends me a really long message at the end saying that I push too much, and she kind of freaked out. So what should I do?

Learn a lot of self control, you ruined any chance with this girl, so you learn not to do it again.
You were only seeing each other not in a committed relationship, she would have been free to even date other guys at this point. She ran and for good reason, you sound very controlling and most women will never want this

Apologize for being an out of control controlling idiot, and if she forgives you but won't date you any more, say thanks and leave her alone.

Sometimes we learn our lessons to late to help today, so keep that in mind for tomorrow.