The International Court of Justice has found it is "plausible" that Israel has committed acts that violate the Genocide Convention. In a provisional order delivered by the court's president, Joan Donoghue, the court said Israel must ensure "with immediate effect" that its forces not commit any of the acts prohibited by the convention.
Further you are using a variation of the Argumentum ad populum logical fallacy. It's immaterial which countries agree or disagree. In the end it's the court that matters.
Ad populum fallacy refers to a claim that something is true simply because that’s what a large number of people believe. In other words, if many people believe something to be true, then it must be true.