The pope, invoking the image of Jesus and his family after Christmas, said he was praying that the Holy Family "keep watch on all the families of the world, especially those who face difficult conditions."
"Likewise, help men of culture and political leaders so they can defend the family institution based on marriage and sustain it in facing the grave challenges of present times," John Paul said, addressing pilgrims and tourists in St. Peter's Square.
John Paul didn't specify the threats to traditional families, but in the past year he has spoken out repeatedly against countries and local governments that have legalized or are considering legalizing gay marriage.
Earlier this month, John Paul said that attacks on marriage and family were becoming stronger and more radical by the day.
He has also denounced initiatives that equate unmarried couples with married couples by granting them legal recognition and social benefits.
The pontiff also prayed Sunday for the victims of thein Asia, and called for international relief efforts.
"The Christmas holiday has been saddened by the news that comes from Southeast Asia about the powerful earthquake which struck Indonesia, with consequences in other countries, including Sri Lanka, India, Bangladesh, Myanmar, Thailand, Malaysia and the Maldives," John Paul told tourists and pilgrims at St. Peter's Square.
"Let us pray for the victims of this enormous tragedy and assure them of our solidarity for all those who suffer, while we hope that the international community acts to bring relief to the stricken populations," the pontiff said, speaking from his studio window overlooking the square.
In his message Christmas Day, John Paul shared his fears about Iraq, Sudan and other hot spots and expressed his hopes in a Christmas message Saturday that peace-building efforts will bring the world a more tranquil future.
"Babe of Bethlehem, Prophet of peace, encourage attempts to promote dialogue and reconciliation, sustain the efforts to build peace, which hesitantly, yet not without hope, are being made to bring about a more tranquil present and future for so many of our brothers and sisters of the world," John Paul said Saturday, slowly pronouncing each word and often pausing to catch his breath.