Nah, alot of retailers now utilize the square as a payment processor.
What it says with an international card is "This could be a fraudulent transaction" and it auto cancels the order with no explaination. The retailer has to go into the payment processor and reinstate the charge and click "I accept responsibility for this charge" and alot of stores just don't care to.
I had it happen to me recently, and i had to show up in the store and the guy said, oh, this was a legit charge, and ran it through.
What you should have told them is that you hereby order them to accept your credit card.