In a strongly-worded letter to the heads of national bishops' conferences and religious orders, the pope demanded "close and complete" cooperation with a new child protection watchdog he has established at the Vatican.
"Families need to know that the Church is making every effort to protect their children," he said.
The Pontifical Commission for the Protection of Minors has been given a brief to drive reform on an issue that has severely damaged the Church's authority and reputation around the world.
The full commission meets for the first time in Rome tomorrow.
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In his letter published today, the pope said families needed to know they could turn to the Church in confidence.
"Consequently, priority must not be given to any other kind of concern, whatever its nature, such as the desire to avoid scandal, since there is absolutely no place in ministry for those who abuse minors."
Francis's letter follows the announcement last month that 10 priests and two Catholic lay workers in the Spanish city of Granada have been charged with the sexual abuse of altar boys between 2004 and 2007.
The Granada arrests came after a former altar boy, now 25, wrote to Francis to say he had been molested by priests from the age of seven to 18.
The pope called the man back and told him to go straight to his bishop, to whom the pontiff wrote with orders to open an investigation.
"How did I receive this news?" the pope said of the episode in November. "With great pain, very great pain, but the truth is the truth and we should not hide it.