Most Helpful Girl
Most girls are still self-conscious about themselves and you staring at them makes them nervous. Feeling that you have to compete with Angelina Jolie or Kate Moss isn't exactly helping with growing up and changing into a woman :D.
If they have never seen you or have never talked to you, they have no reasonable reason, to hate you. They just feel nervous about the attention you are giving to them, they're uncomfortable with themselves, not you. :)
You can help the situation by smiling, for example. Being friendly. :)