You could create a law that says regional/national advertising requires a company or person be in that jurisdiction and that they must hold $$$ in bond as a guard against false claims.

This would prevent foreign ads targeting domestic users, and/or give you an organization to sue domestically. In this case, it's likely that the Israeli govt would work through a US based org, and that in court that case would likely fail for free speech rights. Though a case/org in another nation might not hold up under that nation's laws.

Or you could just hold the platforms liable for the advertising they host, and leave it up to the platforms to decide how best to weigh the trade-offs between that liability and their, to date, woefully underwhelming moderation.

Because I'd prefer to preserve the freedom of speech to it's fullest extent as opposed to corporate or govt censorship.

Who has standing to sue? We already see the current President using lawsuits to allow media companies to bribe him.

The injured party... in the above case, the UNRWA would sue the org paying for the ads in the target location, for example the US org paying for the ads themselves in the US.