Only Russia/China can stop this .
Neither of them can stop this.
It's not about lack of capacity but about strategic interests.
Tbh, war with Iran is working in their favors.
It's being reported that US is considering lifting sanctions from Russia to ease oil and gas supply. India already received 30 days waiver and is buying Russian oil stuck on seas.
Infact, Russian oil and gas demands are rising and they are gaining financially.
A crippled Iran would rely heavily on China. It would give China an opportunity to get oil at much discounted rate in future and also spread it's economic leverage in the region.
As I said earlier, major powers of the world are having strategic silence. They will intervene to get ceasefire only when economic consequences will start going out of control.