How can I help a friend out so she is not looking for love in the wrong places?

This probably sounds stupid but I need help with a friend. You see she is only 14 years old and has never had a bf. She's tried going out with old guys like in their 20s or by trying to hook up with some stranger that accidentally texed her and claims to be 16. Well now she is going online on dating websites but I'm afraid that she might get into trouble or get hurt. I've tried talking about it to her and she gets so pissed at me and claims I'm always jealous, or that I'm always trying to ruin everything for her, which in fact is not true. She is like a sister to me and I want her to know that she is pretty enough to find someone and that she's a really good person. but she doesn't believe me