Pope Francis is feeling "the pain and horror of this absurd violence" following the killing of a priest at a church in France.
The Vatican condemned the "barbarous killing", saying the Pope was horrified by the news.
"We are particularly shocked because this horrible violence took place in a church, in which God's love is announced," Vatican spokesman Father Federico Lombardi said.
He said the Pope "condemned in the most radical way any form of hate".
Muslim leaders say they don't want to "taint" Islam by burying Adel Kermiche who slit the throat of 85-year-old priest Father Jacques Hamel.
Islamic State's Amaq news agency released footage showing French attacker Abdel-Malik Nabir Petitjean urging Muslims to destroy the country.
The self-styled Islamic State has released a video of the French church attackers pledging allegiance to the group.