"Tonight, our hearts are in Bethlehem, where the Prince of Peace is once more rejected by the futile logic of war,” he told about 6,500 faithful, referring to Jesus Christ.
In his message, the leader of the Catholic Church also urged people not to be obsessed with worldly success and the "idolatry of consumerism."
On Christmas Day, the pontiff will lead the traditional "Urbi and Orbi" prayer (Latin for “To the City and To the World”).
Israel has pounded the Gaza Strip since a cross-border attack by the Palestinian group Hamas on Oct. 7, killing at least 20,424 Palestinians, mostly women and children, and injuring 54,036 others, according to health authorities in the enclave.
Around 1,200 Israelis are believed to have been killed in the Hamas attack.
The Israeli onslaught has left Gaza in ruins, with half of the coastal territory's housing damaged or destroyed and nearly 2 million people displaced within the densely-populated enclave amid shortages of food and clean water.