What should i do about a girl i don't like?

My friend doesn't like this girl and eventually i didn't like her either. She's in one of my cles and on Wednesday i notice her look at the TA like she liked him and i told my friend cuz i thought it was funny but i guess HER friend noticed i was talking about her and told her and she starred at me for the rest of the period. Today i looked over there and her and her friends were looking at me. It feels uncomfortable. What should i do dogg her back or get into a fight cuz i would do either if it comes to it. Tell me your suggestions on what to do and please don't say anything dum on your answer cuz this is serious.