The 82-year-old pontiff delivered the traditional address known as "Urbi et Orbi" -- Latin for "To the City and the World," sending a message of hope to the world's afflicted.
The pope was not injured when an assailant, identified as Susanna Maiolo, lunged at him during the Thursday night mass and pulled him down, Vatican spokesman Federico Lombardi said. However, Cardinal Roger Etchegaray, who was nearby, fell and broke a leg.
Maiolo, 25, is the same woman who tried to attack Benedict on Christmas Eve last year, Lombardi said.
She was detained by Vatican police and taken to a mental institution, he said.
The pope was quickly helped to his feet by his aides -- prompting cheers from the crowd -- and the service resumed, Lombardi said.
In his address, the pope recognized those who have been affected by the global financial crisis and by war and conflict and said, "May your hearts be filled with hope and joy for the savior has been born for us."
He expressed solidarity with the victims of natural disasters and poverty, especially mentioning those who were forced to flee their homes.
He then sent Christmas greetings in 65 languages with tens of thousands gathered before him.
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