How can I tell the person that has a Crush on me that I'm not interested right now?

I know this can be a Difficult question to answer but I really don't know how to. Yes, it is the same girl that I recently talked about but I don't want to hurt her feelings either. I just don't know how to tell the right words to tell her. It has indeed put me into a weird and awkward situation. Hence why I am asking this question.