I'm not in favor of shouting "Antisemitism!" every time a Jew anywhere has an altercation with a non-Jew. But this case looks pretty straightforward, since the attackers explicitly told their victims they were being attacked as Jews.
I know basically nothing about Australia, and cannot give a clue about the context of this attack. The report studiously tells us nothing about it either, for whatever reason. Is it out of the blue? In the last sentence there's a hint it may be part of a pattern, but there's no information about that, either. The only thing we are able to deduce is that there is no obvious connection to, say, Israeli politics. Indeed, the word Israel is never mentioned nor alluded to.
Australian readers should feel free to enlighten us, in the comments if they wish.