They won't, not now anyway. The Soviet Union went as far as to fund wars against "israel", but China is clearly far more interested in Socialism In One Country and forming amicable ties with the rest of the world — including the capitalist shitstates — rather than spreading socialism like the USSR did.

Not necessarily a bad thing since I understand where they're coming from (and we know which of the two have managed to prevent a capitalist counter-revolution), but god I wish they did a bit more sometimes.

Genuinely aggressive Chinese sanctions on "israel" would cripple it in months combined with Palestinian resistance, but it also would create hostility with the US, signal to the Global South that they're willing to sanction states that don't do what China wants like the US does, and damage their reputation of being a peaceful superpower that they've been building for the last few decades.