In a nearly 5,000-word message sent on the feast day of St John Vianney, patron of parish priests, the Pope acknowledged the "pain" of priests who "feel themselves attacked and blamed for crimes they did not commit".
The pontiff said on Sunday that priests have shared with him "their outrage at what happened and their frustration that for all their hard work, they have to face the damage that was one, the suspicion and uncertainty to which it has given rise, and the doubts, fears and disheartenment felt by more than a few".
Francis said "without denying or dismissing the harm" caused by the scandals, "it would be unfair not to express our gratitude" to priests who have fulfilled their duties "faithfully and generously".
The Pope said the Church is "fully committed" to reforms to ensure "that the culture of abuse will have no time to develop, much less continue".
He added that "if in the past, omission may itself have been a kind of response, today we desire conversion, transparency, sincerity and solidarity with the victims".
Last August, Francis issued a letter to Catholics around the world condemning the "crime" of priestly sexual abuse and cover-up, and demanding accountability, in response to revelations in the US of decades of misconduct by the Catholic Church.
In the letter, the Pope also begged forgiveness for the pain suffered by the victims and said lay Catholics must be involved in any efforts to root out abuse and cover-ups.
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