I'm going to tell a girl I won't date her because of her height
Why tell her her height's an issue?
I'm looking for someone taller than me to spend my life with.
You shouldn't do this. If you don't want to be with her then fine, but you shouldn't be cruel when breaking things off with her.
I can't date anyone if I don't like their height. That's just how things are.
I get it. Everyone has a preference, but you should just tell her you're not interested and keep the height requirement out of it.