"I realize how much the pain of recent years has weighed upon you," he said, at a prayer service with the bishops in Washington on the first full day of a US visit.
"And I have supported your generous commitment to bring healing to victims -- in the knowledge that in healing we too are healed -- and to work to ensure such crimes will never be repeated," he said.
The pope disappointed many American followers by deciding not to meet with the victim's of sex abuse by priests, but he was not able to avoid the issue altogether.
Experts speaking at the Vatican said in 2012 the number of abused American minors is probably close to 100,000.
Besides the abuse itself, bishops and the Vatican have been accused of protecting suspected abusers and giving alleged victims the cold shoulder.
In June, Francis sacked two US bishops accused of looking the other way: the archbishop of Saint Paul and Minneapolis, John Clayton Nienstedt, and his aide Lee Anthony Piche.
And earlier this month the Vatican replaced Bishop Robert Finn of Kansas City, who resigns in April after failing to report a priest accused of pedophilia.
Since the first revelations in the 2000s, the church has spent USD 3 billion on legal costs and rehabilitation for offenders, according to watchdog Bishop Accountability.
