The ban on the 'burkini', which covers a woman's head, comes after a spate of Islamist extremist attacks in France.
Recent attacks include a man mowing down crowds in Nice on Bastille Day, killing 85, and the murder of a French priest while he was conducting Mass in Rouen.
Five towns have banned the burkini, and the French Interior Minister Manuel Valls has said it entrenches the "enslavement of women".
France, a country known for its secular values, has already banned the veil in public.
Bishop Nunzio Galantino, the head of the Italian Bishop's Conference, told Corriere della Sera: "We must learn to live together and this means being aware of the symbols of other cultures and accepting them when they do not impinge on our safety.
"I find it hard to understand France and this war on symbols... when it justifies the derision and the vulgar ridiculing of the religious sensitivity.
"Everyone must have the freedom to externalise his or her own faith. If a Muslim woman wishes to wear a veil, she must be able to do so. Similarly, if a Catholic wishes to wear a cross."