Only Europeans claim that United States of America can't be called "America."
Actually it's even the contrary, Only "Americans" claim that UNited States of America is called "America". In French we call you specifically Etats-Uniens or Ricains, it is more relevant, in Spanish they also call you Estados-Unidenses.
And this is not only Europeans, the Chinese call your nation "Meiguo" whereas the continent is "Meizhou", you see they are differentiated. You are the only ones considering your nation incorporating the whole continent by "America" or "Americans".