Darn, relationship problems, please help...?

at the moment, im infatuated with a male friend of mine and its reciprocal. the problem is, we're only 18 and im not keen into having relationships right now! and we've only known each other for only 3 months. i want to wait till it's the right moment, get to know each other better and see how things goes. but he thinks im only playing around.. sigh, so what do i do? i really like this guy.