When I tried signing up for my Facebook account using Gmail, I had the same problem. You might try using Yahoo mail or other reputable email service to see if they let you register in that way. Also, you might be able to submit a help ticket or help request to Facebook via email if they still won't allow your Facebook account registration.
One other thing you should do is to add Facebook to your whitelist of accepted email recipients and also check your spam folder as there's a chance the confirmation email is simply in the recycle bin.