It wouldn't be pedophilia because you're not that far apart in age. You'd have to be at least 5 years younger than him for that to be counted as pedophilia, I think. If he's 18, and your underage, you'd have to get a parent's consent, right? Otherwise he could get in trouble. (That's what the laws are here, I dunno about where you live.)
Also, if you're friend already likes him, and you like him, I wouldn't even go for it. I mean, do you think it could cause a fight? What if you start dating him, and your friend gets jealous?
And, what if you have a bad break up? Do you want to lose him as a friend?
I'm not saying that any of this will happen, I'm just saying it could happen. I'd really think about it, hun. Sometimes you can just have a bit of a crush on your friends, that doesn't really mean anything. :/
But, at the same time, if you really like him, and want to try it. Go for it. Just be careful.
I hope I'm not just rambling here. Sorry, if I was no help. Love ya!