A Vatican spokesman told The Local on Friday that there was no truth to the report, published in Clarín on Thursday.
But in a follow-up article, the Argentine daily said the phone call was confirmed by three important sources within the Vatican.
The sources reportedly told Clarín that Pope Francis called al-Assad this week “to ask him to do everything he could to stop the repression against the rebels and adopt a more conciliatory tone”.
Al-Assad has been waging a violent campaign against opposition groups for more than two years. Repression of protests in spring 2011 quickly descended into civil war, which has now left more than 100,000 Syrians dead and prompted over two million to flee the country.
A reported chemical weapons attack against civilians in August prompted international leaders to discuss military intervention in Syria, a move strongly opposed by Pope Francis.
In a letter addressed to Russian President Vladimir Putin, a key al-Assad ally who is currently presiding over the G20 meeting in Moscow, the pontiff spoke out against “the futile pursuit of a military solution”.
“The leaders of the G20 cannot remain indifferent to the dramatic situation of the beloved Syrian people...let there be a renewed commitment to seek, with courage and determination, a peaceful solution through dialogue and negotiation between the parties,” Pope Francis said.
But it appears that the pontiff’s plea has fallen on deaf ears. Last night, Prime Minister Enrico Letta, in Moscow for the G20 meeting, said that no progress had been made on Syria.
“The G20 has now finished the dinner session at which the divisions about Syria were confirmed,” Letta said in a tweet.