Article 19 of the Universal Declaration of Human Rights is a guarantee of freedom of expression: “Everyone has the right to freedom of opinion and expression. This right includes freedom to hold opinions, without interference, and to seek, receive and impact information and ideas through any media and regardless of frontiers.”
However, in the same Article, there are provisions for restrictions:
(a) For respect of the rights or reputations of others;
(b) For the protection of national security or of public order (ordre public), or of public health or morals.
Facebook is violating International Law. Given that it is collaborating with governments (Israel, US) how will this law apply to it? We know from September 2016 that "Facebook Is Collaborating With the Israeli Government to Determine What Should Be Censored."