How can i tell him that i'm not interested without hurting his feelings?

I would avoid him a little longer and see if he backs off.If he doesn't,simply tell him you don't want to hurt his feelings,but are not interested.People lack honestly so much these days and we don't have to be mean to be honest.He should appreciate you being upfront.You could also say "you are not my type".I don't know if that one would hurt though..