The pope said he hopes the new year will bring peace, justice and liberty to the world, Vatican Radio reported.
"Peace requires the force of meekness, the force of nonviolence of truth and of love," he said.
He noted the church is celebrating the feast of Mary and the World Day of Peace Wednesday.
He called for people to acknowledge violence and to work toward building a just society during his address, titled "Fraternity: the Foundation and Pathway to Peace."
The pope deviated from his prepared speech and commented on a letter he recently received, the report said. He said the writer wanted to know: "What has happened in the hearts of men, in the heart of humanity? It is time to stop. It is time to stop."