My cousin and I were in Paris in 1983 during one of the periodic student riots (my father had been there in 1968 during those riots). I remember watching a protest from the first level of the Eiffel Tower. They were burning someone in effigy, and smoke was everywhere. As a symbol of the city, it's not surprising the bad guys and loonies would make threats to it.
Coincidentally, I'm about 80% through David McCullough's "The Greater Journey: Americans in Paris," about Yankees who flocked to Paris in the 19th century to study painting, sculpture, medicine, and the other arts. I'm at the part where the tower has just been constructed.