"May Christ's spirit of forgiveness prevail in the face of these barbaric acts."
Cardinal Robert Sarah also responded to the news of the attack on the basilica.
He wrote on Twitter: "Islamism is a monstrous fanaticism which must be fought with force and determination ... Unfortunately, we Africans know this too well. The barbarians are always the enemies of peace. The West, today France, must understand this."
Mohammed Moussaoui, president of French Council of Muslim Faith, condemned the terrorist attack and asked French Muslims to cancel their festivities for Mawlid, the Oct. 29 celebration of the Prophet Muhammad's birthday, "as a sign of mourning and solidarity with the victims and their loved ones."
Other attacks took place in France Oct. 29. In Montfavet, near the southern French city of Avignon, a man waving a handgun made threats and was killed by the police two hours after the Nice attack. Radio station Europe 1 said the man was also shouting "Allahu Akbar."
Reuters also reported a knife attack on a guard at the French consulate in Jeddah, Saudi Arabia.
Archbishop Éric de Moulins-Beaufort, president of the French bishops' conference, wrote on Twitter that he was praying for Catholics in Nice and for their bishop.
French president Emmanuel Macron visited Nice following the attack.
He told journalists: "I want to say here first and foremost the support of the whole nation for Catholics, from France and elsewhere. After the assassination of Fr. Hamel in August 2016, it is once again the Catholics who are attacked in our country."
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He underlined the point on Twitter, writing: "Catholics, you have the support of the entire nation. Our country is our values, that everyone can believe or not believe, that every religion can be practiced. Our determination is absolute. Actions will follow to protect all our citizens."
This report has been updated to include Emmanuel Macron's comments.