As part of his diplomatic efforts, Francis also met last November with a group of Palestinians affected by the conflict.
"I have asked that studies be carried out into this ugly ideology of our times, which cancels out the differences and makes everything the same," the pope said.
Pope Francis has called several times for an immediate ceasefire in Gaza and for the release of all hostages taken by Hamas.
In previous guidance from 2016, the Vatican said the ashes must be kept in "sacred places", and therefore neither at home, divided among family members nor scattered to the wind.
The Vatican has been vocal in calling for the release of all hostages as well as a ceasefire.
Currently, the official Vatican position is that it neither confirms nor denies possession of Herodian Temple objects such as the golden Menorah, sacred tables, altars, and priestly garments.
WJC said its “Kishreinu” initiative was a response to Nostra Aetate, the landmark 1965 document that modernized the relationship between the Roman Catholic Church, Judaism and other religions.
Cardinal Pietro Parolin, the Vatican's Secretary of State, said the Holy See remains firmly convinced that a two-state solution is the only way to guarantee lasting peace in the region.
The historic elevation of Latin Patriarch Mgr. Pierbattista Pizzaballa at the Vatican may bring more of a papal focus on the holy city
The letter, dated December 14 1942, proved Pope Pius knew of extermination camps killing Jews and Poles.