Police in the Australian state of Victoria summoned Pell, 76, to appear in court there in July to face historical sexual assault offense charges.
"There have been leaks to the media," he said. "There has been relentless character assassination, relentless character assassination."
Pell has not been asked to resign by Francis, who has vowed zero tolerance for sexual-related offenses. The pontiff granted Pell the leave of absence "so he can defend himself," the Vatican said in a statement Thursday.
"The Holy See has learned with regret the news of charges filed in Australia against Card. George Pell for decades-old actions that have been attributed to him," a statement from the church said. "The Holy Father, having been informed by Card. Pell, has granted the cardinal a leave of absence so he can defend himself."
In 2014, Francis appointed Pell the Vatican prefect of the secretariat for the economy. Pell, who was ordained as a priest more than 50 years ago, is the highest-ranking Vatican official to face charges in the Catholic Church's multiyear sex abuse scandal, according to the AP.
"I am looking forward finally to having my day in court," Pell said on Thursday. "I am innocent of these charges. They are false. The whole idea of sexual abuse is abhorrent to me."
Pell voluntarily spoke with Australian police officials in Rome in 2016 about alleged sexual assaults in Ballarat, Australia, from 1976 to 1980 and in East Melbourne from 1996 to 2001.
The Vatican said Pell has "openly and repeatedly" condemned abuse against minors and noted his support for the Pontifical Commission for the Protection of Minors.
ABC News' Phoebe Natanson contributed to this report.