One has to ask why your relatives in Argentina who are so upset at the anti-Israel sentiment don't just move to their so-called ancestral homeland. I imagine there is some level of anti-semitism in Argentina, but as in the rest of the world, it is Israel's policies, and zionism, that most people are outraged by. In order for us to judge whether this graffiti is "anti semitic" please do tell us what else you saw, besides "end the occupation" which is of course not the least bit anti-semitic.
Police disperse hundreds in brawl in Kafr Manda, northern Israel (Haaretz)
from the article: What can be done to stop the rise of anti-Semitism in Argentina?