I would be surprised if a US mortgage company would be able to fund a loan on a Spanish house. If you were to default then the bank gets the house, but if it isn't in the US then how could they get the house?
I found this on some site:
I live in the U.S. but I would like to purchase a property in another country. Can I get a mortgage through you on a foreign property? In order for a consumer to apply for a mortgage on a foreign property, you must apply through a bank, broker or financial institution offering mortgages in that particular country. You cannot apply for a foreign mortgage (non-U.S.) at our website in the United States.