Emiliano Fittipaldi makes the accusations against the Pope in his new book Lussuria ('Lust') which will be released in Italy on Thursday.
Fittipaldi claims that 1,200 complaints of child sex abuse were taken to the Pope in his first three years of papacy. He writes that in Italy, a number of priests have been convicted of abuse but the church did not take any canonical action against them.
The author also suggests that Australian cardinal George Pell, who has been accused of protecting abusers in his archdiocese, has remained in a senior position despite the complaints against him.
Author Emiliano Fittipaldi
In an interview with the Guardian, Fittipaldi said: "The principle message of the book - the problem - is that the phenomenon of paedophilia is not being fought with sufficient force. Across the world, the church continues to protect the privacy of the paedophiles and also the cardinals [who protect them]."
"Francis is not directly defending the paedophiles, but he did close to nothing to contrast the phenomenon of paedophilia," he added.
Fittipaldi also claimed that the church favours priests who practice omerta - a code of silence - when it comes to the issue of abuse.
"In all the Catholic countries, in Italy, Spain, South America, the sexual crimes of the priests are hard to tell. There is a kind of auto-censoring, on the part of journalists and victims because of the shame and because the culture of the church is very strong," Fittipaldi said.
Last week a priest in Florida filed a lawsuit against the Diocese of West Palm Beach, claiming the bishop punished him for exposing child abuse committed by his colleague.
Six months ago, Fittpaldi and fellow journalist Gianluigi Nuzzi were acquitted at a tribunal at the Vatican for publishing confidential financial documents in a scandal dubbed "Vatileaks".