I don't think it's necessary to suppress one's sexuality to be a friend. I can let a female acquaintance know I am aware of her attractiveness (friendly flirting) without giving the impression that's the only thing about her that interests me. It's in the eyes, the conversation, the choice of activities, the nonverbal cues, the effort you put into keeping in touch.

That said, however, you can't fake the attitude that values someone as a friend and not just as a potential sex partner. At some point that will probably be tested, and it should, because the friendship is the foundation for whatever else you'll build together.