Yes or no question: what to say when someone asks you if you like them?

Alright... so there's this girl from my school and my friend hangs out with her and tells me that apparently she really likes me. (but she doesn't know that I know that.) She's kind of cute and nice and all, but I don't get into relationships with anyone right now. I kind of do like her a bit, but I don't want to go out with her. I'd love to be her good friend though. We started texting each other a few days ago, and today when I get home from school her brother texts asking if I like her. I'm guessing she asked him to ask me that to find out if I like her back, and even if she didn't and her brother just wanted to know when he saw her texting me, my answer will inevitably reach her anyway. If I say no, it might hurt her feelings and she might not want to be friends or hang out or anything anymore. Obviously if I say yes she'll like run up and hug me and ask if I want to go out with her first thing tomorrow, which I also don't want to happen. What should I say? What I want to do is give him an answer that tells him no, but makes her dubious and makes her still like me a little. I'm not sure what to do.