Pope Francis has spoken of his closeness to victims of attacks in Britain, Norway and Afghanistan and their families.
In his Sunday Angelus in St Peter's Square, the Pope expressed his sadness over the attacks "which caused many dead and wounded".
He said he was praying for peace as he warned that violence would only lead to more violence.
"I express my closeness to the families of the victims and I pray, please, abandon the path of violence, which is always a loss, a defeat for everyone," he said.
"Let us remember that violence begets violence."
Britain has been mourning the death of Conservative MP Sir David Amess who was stabbed to death while meeting constituents inside a Methodist church last Friday.
Police have arrested a 25-year-old Briton in connection with the attack and are treating his death as a terrorist incident.
Sir David Amess was a devout Catholic. The head of the Catholic Church in England and Wales, Cardinal Vincent Nichols, called his death "a painful loss" and said he would be "sorely missed".
"This death throws a sharp light onto the fact that our Members of Parliament are servants of the people, available to people in their need, especially in their constituencies. This horrific attack, as David was undertaking his constituency surgery, is an attack on our democratic process and traditions," the cardinal said.
"David carried out his vocation as a Catholic in public life with generosity and integrity. He served in Parliament for four decades and was respected by all political parties across the House. His untimely death is a great loss."
Also on Friday, at least 41 people were killed and dozens more injured during a suicide attack by the so-called Islamic State at a mosque in Kandahar in Afghanistan.
These attacks came two days after a man went on the rampage in Norway with a bow and arrow among other weapons, killing five.