Friendzone her at once, or lie and say you're interested in another girl. Just say you fancy someone else then she should get the hint and stop flirting with you. She could be a socially awkward person who is just trying to be your friend but she is coming across as flirty to you. You need to just be straight with her, and ice weapons are always best.
Pretty much this.
Georgie Porgie, pudding and pie,
Kissed the girls and made them cry;
When the boys came out to play,
Georgie Porgie ran away.