The Mossad said to have thwarted an Iranian plot to attack a gathering of Iranian dissidents in a Paris suburb in June. On Thursday, Israel lifted censorship on the publication of the operation.
The Mossad gave Germany, France and Belgium crucial intelligence information about the attack, which led to arrests of a cell headed by an Iranian diplomat.
The opposition rally was due to include a speech by U.S. President Donald Trump's lawyer, Rudy Giuliani.
According to news reports, Mossad agents tracked down suspects in several countries.
Prime Minister Benjamin Netanyahu alluded to the operation in a speech he gave in July: "I call on the leaders of Europe: Stop funding the very regime that is sponsoring terrorism against you and against so many others. Stop appeasing Iran."
The reason for the censorship is unknown and it's not clear why Israel's intelligence agency changed its position Thursday evening to lift the censorship to publish the report.
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