Speaking on Vatican Radio, he also stressed that Pope Benedict XVI was prepared to meet again with victims of paedophile priests.
"Apart from the attention we must pay to the victims, we must pursue cooperation with the relevant civilian judicial and penal authorities, in line with the legal and other situations in each country," he said.
In a reference to a letter on priest sex abuse to Irish Catholics the pope published last month, Lombardi said that "in the context of attention to victims, the pope has written that he is available for new meetings" with victims.
Senior clerics were accused of protecting guilty clergy by moving them to other parishes -- where they sometimes offended again -- instead of handing them over to be tried.
The 82-year-old pontiff has himself faced allegations that, as Cardinal Joseph Ratzinger when he headed the Vatican's watchdog for morals and doctrinal issues, and earlier as the archbishop of Munich, he failed to take action against predator priests.
In the letter to the Irish in mid-March, the pope expressed "shame and remorse" for the sexual abuse of children by priests and conceded that "serious mistakes" were made by Irish bishops in responding to allegations.
The pope also said priests and religious workers guilty of child abuse "must answer" for their crimes "before properly constituted tribunals," and said he was willing to meet victims again.
"This is the only way to restore a climate of justice and full confidence in the institution of the Church," Lombardi said, adding that "transparency and rigour impose themselves as urgent requirements."
Lombardi also spoke about the process of priest selection and education, saying it is "the premise for an effective prevention of possible abuses."
"Reaching a healthy maturity of personality, also in terms of sexuality, has always been a difficult challenge; but today it is even more so," he said.
In the education of priests, it is crucial to address "the sense and importance of the meaning of sexuality, chastity and of emotional ties," Lombardi said.
The Vatican has dismissed suggestions that the Church's rule of celibacy for priests can lead them into temptation.
Lombardi also reprimanded the media for their handling of the scandal, saying "the media have not worked enough, especially in countries where the Church's presence is more important."
As an example, Lombardi cited a recent national survey of child abuse in the United States he thought was overlooked by media.
Out of 62,000 child abusers identified in 2008 in the United States,"the group of Catholic priests is so small that it was not even taken into consideration," he said.
Source: AFP Global Edition