Argentines are mostly European (like Americans), I believe, descended from Italian, French, German, and Spanish colonists, with some Arab, Russian, and Japanese, etc. as well. The current demographics state that 97% of the population is of European or partial European descent. Argentina also boasts the largest Jewish population in South America.
Applying racial demands for casting Argentine characters in theatre is as silly as demanding that Cleopatra (who was Greek) be cast to resemble a Nubian, merely because Egypt is located on the continent of Africa.