So I liked this girl and we hung out a couple of times. She told my friends she liked me. We started exchanging text everyday. She flaked out on me one time and I kinda freezed her out(ignore) for a couple of days. Recently we hung out again and she told my friends(who i introduced her to) that she feels like we're just now friends because I put her in the friend zone.

So did freezing her out backfired or is she just saying that to my friend but still have feelings?

Freezing didn't 'backfire'. She had to be punished for flaking on you; if she can flake without consequence, then she'll continue to do so. Stand your ground on that sort of thing. It's pretty clear that it worked, as far as establishing what's acceptable behavior from her and what isn't. Remember that even if you don't get any pussy from her, you weren't going to get any pussy from her when she was standing you up. All you've done is greatly improve the situation for yourself.

I'd call her bluff and go fuck her. Sounds like she's whimpering about having been punished, even though she deserved it. Don't explain, argue, or justify yourself as to why you froze her out. Just get on with fucking her. If you really really get painted into a corner where you feel you must say something, say "standing people up is bullshit, that's just common sense" and leave it at that. Don't get into a big drama emotional debate about it. If you 'do drama' with her, that gives her the justification she needs to bolt because it's 'your fault'. Wheres the "yes, right, that was bullshit, moving right along now..." approach makes the point and keeps the action going in the intended direction - her pants.

I once told a girl that I saw her like a bratty little sister.

She called me a bit sick and she found it very weird, seeing as I liked her. She says that its a bit strange. She has acted strange ever since that moment.

I think girls dont take it kindly when you kind of disqualify her, even though she knows you like her. Which in itself is weird.

I don't think u wanna call a girl a sister if ur trying to get with her. It's a straight ticket to the friends zone. Just based on experience