Everybody here is complaining about how they would rather just get a response, though. I mean, I could just be honest.
Well did you two talk at long lengths in messages and start texting back and forth? If so, then you do need to say something and not blow her off, but if you two exchanged a handful of messages then blowing her off is not that big of deal.
Yes I hate it too, but ONLY if it was after a LOT of back and forth. That's when it sucks, because you are confused as fuck on how you screwed it up.
If it is a lot of back and forth, then I'd just say, "Hey I like talking to you, and I know this may not be what you want to hear, but I don't see this being anything more than a friendship. I'm sorry, but I figured I'd be honest."
That should smooth it over.