Leo, who was elected last week to succeed the late Pope Francis, has made repeated calls for peace in the early days of his papacy. His first words to crowds in St Peter's Square were "Peace be with all you".
He returned to the issue while addressing members of the Eastern Catholic Churches, some of which are based in conflict-ridden places such as Ukraine, Syria, Lebanon and Iraq and often face persecution as religious minorities.
"The Holy See is always ready to help bring enemies together, face-to-face, to talk to one another, so that peoples everywhere may once more find hope and recover the dignity they deserve, the dignity of peace," Leo said.
"War is never inevitable. Weapons can and must be silenced, for they do not resolve problems but only increase them. Those who make history are the peacemakers, not those who sow seeds of suffering," he added.
Pope Leo warned against the rise of simplistic narratives that divide the world into good and evil. "Our neighbours are not first our enemies, but fellow human beings," he said.
On Sunday, the pontiff called for an "authentic and lasting peace" in Ukraine, a ceasefire in Gaza, the release of all Israeli hostages held by militant group Hamas, and welcomed the fragile ceasefire between India and Pakistan.
Leo spoke to Ukrainian President Volodymyr Zelenskiy on Monday in his first known conversation with a foreign leader as pope. He offered to facilitate peace talks as world leaders come to his inauguration mass, the Ukrainian leader said.
Zelenskiy hopes to be present for the event in St Peter's Square on May 18 and is ready to hold meetings on the sidelines, the Ukrainian leader's chief of staff Andriy Yermak told Reuters on Tuesday.
