I would suggest lobbying MPs but that seems a risky move in the UK.
Back action to bring those responsible and those who support this to the ICC to face trial, that is all we can do.
Be vocal on here too, condemn what is happening killing of civilians. Which will at least provide evidence you don't support crimes against humanity by any of the sides here, given Hezbollah are being dragged in and we have Islamic Jihad and other groups in volved.