How can I be nice to girls ?

Many men are attracted to girls so they are nice to them. But I am not attracted to girls at all. So I don't talk nice to them, for me it is like straight men talking to male or grandmother. Besides even if I was attracted to girls, I don't want to talk nice to them. Because I don't want to think I am flirting with them, I don't want them to think I like her in romantic way. Some girls think of me as very cold, mean person. I don't wan them to think of me that way.