The Pope told the five survivors, an unknown number of whom had been abused by priests, that clergy and bishops would be held accountable when they abuse or fail to protect children.
Many abuse survivors are angry at how the Vatican has dealt with allegations.
The Roman Catholic Church in the US has been embroiled in child sex scandals.
US dioceses have made huge compensation payouts to victims.
The Pope met the five victims, all now adults who had suffered sexual abuse as children, on Sunday morning at a seminary in Pennsylvania, his spokesman said.
The group – three women and two men – had been abused by clergy, family members or teachers, Father Federico Lombardi said in a statement.
Each was accompanied by a family member, he added.
The Pope was “overwhelmed with shame that men entrusted with the tender care of children violated these little ones and caused grievous harm,” he told bishops following the meeting, on the final day of his visit to the US.
He told the victims who were abused by a member of the clergy that he was “deeply sorry” for the times when the abuse was reported, but victims or their families “were not heard or believed,” the Vatican said in a statement.
“Please know that the Holy Father hears you and believes you,” Pope Francis told the survivors.