This happened to me so I want to let you know. You should call them or e-mail them to make sure they will accept you. Or you will have to hectically look for another hotel when your cellphone battery goes down and Internet connetion will be bad. You will have to contact Booking.com so they would help you to find another hotel and cancel the one who rejected you.
To make things completely clear: Xinglin hotel near Xi'an airport does not accept anyone except mainland Chinese citizens.