Father Robert Oliver, a canon law specialist who previously worked at the archdiocese of Boston in the United States where abuse cases came to light a decade ago, was appointed in December.
Oliver, whose official title is "promoter of justice" for the Congregation for the Doctrine of the Faith, said on Tuesday the peak in reported cases was in 2004 with 800 denunciations.
He said he would follow the example of Pope Benedict XVI in calling for more assistance to victims of abuse and promising zero tolerance against abusers.
Oliver said three-quarters of the world's 112 national bishops' conferences had responded to a Vatican request in 2011 to send guidelines on how to fight abuse.
"Each culture has a different way of confronting these issues and problems," Oliver said, citing the example of South Korea where he said the local culture had a taboo on discussing sexual abuse.
He said Africa was a continent with "a thousand cultures" where the issue of abuse still had to be addressed in-depth.
The Vatican has stressed five key points: helping victims, forewarning minors, training future clergy, rehabilitating abusers and working together with civil authorities.
Catholic hierarchy in many dioceses including in Ireland and the US were accused of covering up abuse for decades and simply moving alleged abusers from one parish to another.