Political Memes

So, imagine that it is indeed a call for the destruction of Israel.

That would be at most anti-Israel, unless you're a Racist who thinks "all Jews are the same", since the only way to believe the nation of Israel is the same as the Jewish Religion, which in turn is the only way to justify claims that anti-Israel slogans are always antisemite, is to think that all Jews support and identify themselves and their religion with Israel, i.e. that they're all the same and hence all think the same - a belief which is the purest of racist prejudice.

What's even more racist about claiming that anti-Israel is the same as antisemitic is that many Jews openly oppose Israel, including participating in these very same demonstrations, so by conflating anti-Israel with antisemitism you're straightforward implying that you yourself can define Jewishness better than actual Jews and by applying it to these demonstratiins which were also attended by people who are Jews, you're accusing said Jews of being antisemite, i.e. "Bad Jews".

It takes quite a lot of racism to go around implying that some Jews are anti-Jew because they disagree with the actions of a state that self-proclaims to represent them. In fact that kind of thing is typical of Fascism and Fascist nations.