I feel bad because i may have made this guy think i am into him?

well i know this guy from cl and we have hung out together twice with people from my cl. we have had about 3-4 long convos online, but not days i a row. i made a point of not talking to him too much so that he gets the message. i know that he likes me, but i thought i made it clear i wasnt interested. he just asked me out, but i know im not into him. do all guys get this impression? im 19 and hes 21. im really naive about this because i have no social life, so advice is appreciated. i will report those who answer rudely.