The French Council of the Muslim Faith made the announcement amid a crackdown on extremism in the country, following the beheading of teacher Samuel Paty, who had shown pupils images of Mohammad.
The Paris prosecutor has opened an investigation for "attempted homicide of a person holding public authority".
Around two-thirds of respondents in France (64%), Germany (67%) and Italy (68%) agreed not sufficient action was being taken in Europe. UK respondents agreed but in lower numbers (57%).
Josu Urrutikoetxea led ETA during one of its bloodiest periods when its victims included children bombed to death while sleeping in a Zaragoza police compound
The two small aircraft collided over Loches, in central France, on Saturday afternoon. There are no survivors.
From Saturday, the cities of Lille, Lyon, Grenoble and Saint-Etienne will be designated maximum alert zones.
The officers were on a surveillance mission when they were “taken by surprise” in an industrial area in Herblay, north of Paris