Tell someone, this seems self explanatory, if you don't want this happening, tell a parent, a guardian, or the police. (assuming you mean sexually touching you.) That is considered rape and incest! Just tell a parent, a guardian, the police, or even someone like a teacher or guidance counselor.
How old are you? Is it an uncle and you are female? You can call Child Protection Services if you are under 18, but have you tried talking to your parents first? If both of those sounds too scary, talk to your counselor at school or a trusted neighbor. Pray for guidance.
My grandfather who claimed to be a Christian (he was NOT!!), did the same to me and several of my cousins. I finally got the nerve to tell my parents and that scumbag went to jail. Should've been fried, in my opinion :) that's how I feel about all pedophiles. What your relative did is definitely considered a crime and you need to report it right away! People like that don't normally have only one victim, so you might be helping other kids by speaking out!
If you can't tell your parents then slap the crap out of him if he comes near you again and with your meanest voice tell him get away from you to never ever touch you again. You can't close your eyes any longer, he will just go further and take more advantage of you. Be strong!