The more you try to deny liking someone, the more you end up liking them. I don't know why this happens, I just know that that's what happens. I had issues like that with my ex boyfriend. The more I tried to hate him, the more I ended up liking him. In the end, I just accepted that I still had some feelings for him and it's been easier on me. Plus you can't just stop yourself from liking someone. Having crushes is a very natural thing. You can't force yourself to not have a crush when you do have one.
Also I find it rather unreasonable and highly unlikely that your parents are against you having a CRUSH. They should know that when you're young, having a crush is kinda an inevitable thing and it happens to almost everyone during their teenage years. I mean they were young once, right? So honestly, I think that they're NOT against you having a CRUSH, but instead are against you having a BOYFRIEND or DATING someone at this point in your life. They're two completely different things. A crush is just liking someone. A boyfriend or dating someone has more of a commitment with it. Some parents just want to protect their children from the distractions and the pain that come with dating and liking people so they don't want their kids to date YET, especially since you sound like you're still very young.
I say that you sound young like in your early teens because of the description of your friends. Only kids who haven't gone through puberty yet or are only starting puberty will be against having crushes. Once you're older, you realize that having a crush isn't a bad thing nor is it that huge enough of a deal for you to be against. So your friends are still immature and it's best to just leave them out of it right now.
But I suggest that you do tell your parents about it and say that you're actually trying to stop yourself since you know that it's distracting you. They'll see that you're mature in the sense that you know when something is bad for you. If you still feel uncomfortable talking to your parents, then talk to a counselor at your school. It may seem awkward but they will definitely understand for sure. Kids go through stuff like this all the time and it's the counselor's job to know what to do. Also if you need anyone to talk to, I'll be willing to listen as well since I've been through this and my parents weren't so crazy about letting me date from my early to my mid teenage years either (they finally allowed me during my late teenage years). Just comment on my answer and I'll get back to you as soon as I can :)
Anyway, I wish you luck. Just try not to force yourself into not having a crush on this guy. Just let things go by naturally and even though you have the urge to talk to other people about it, just keep it cool for now and you can rant however much you want to me or your school counselor haha!