The Pope and the Archbishop of Canterbury have both held separate video calls, with the head of the Russian Orthodox Church appealing for him to call for peace in Ukraine.
Patriarch Kirill has been widely criticised for not condemning the Russian invasion and for appearing to support the Putin regime.
During his conversation with the Patriarch, Most Rev Justin Welby expressed 'grave concern' about the war and called it a 'great tragedy.' He stressed the need for an end to the violence and urged Patriarch Kiriill to publicly call for peace.
Lambeth Palace said the Archbishop had spoken of the need to find ways to live as neighbours in Europe without aggression and human suffering following the call of Jesus Christ on his disciples to be peacemakers.
Both leaders emphasised the need to achieve a lasting peace, based on justice, as soon as possible and agreed to continued communication.
In his video call with Patriarch Kirill, Pope Francis said the church must use the language of Jesus rather than politics.
The Vatican said that during the call Pope Francis rejected the justifications for the invasion as a "holy war," saying "today we cannot speak like this.
"Christian awareness of the importance of peace has developed.
"We are pastors of the same Holy People who believe in God, in the Holy Trinity, in the Holy Mother of God: for this we must unite in the effort to help peace, to help those who suffer, to seek ways of peace, to stop the fire.
"Those who pay the bill for the war are the people, it is the Russian soldiers and it is the people who are bombed and die," the pope continued. "The Church must not use the language of politics, but the language of Jesus."
Patriarch Kirill is a close ally of President Putin and has made statements defending Moscow's actions in Ukraine. He is said to regard the war as part of a struggle against sin and pressure from the liberal West.
As a result, some bishops in the Ukrainian Orthodox Church have authorized their priests not to commemorate Patriarch Kirill in their prayers during public worship services.