Just because he likes you doesn't mean you've done anything wrong. Tell him you are not interested. You can't make him like your friend, but as long as you don't go after him and are straight with her, it shouldn't hurt your friendship. And the guy you like either likes you back or he doesn't, there's nothing you can do there either. So really, you don't have to do anything, just be clear with everyone about your intentions.
Just because he likes you doesn't mean you've done anything wrong. Tell him you are not interested. You can't make him like your friend, but as long as you don't go after him and are straight with her, it shouldn't hurt your friendship. And the guy you like either likes you back or he doesn't, there's nothing you can do there either. So really, you don't have to do anything, just be clear with everyone about your intentions.