The pontiff has suggested disinformation is "probably the greatest damage that the media can do".
The Pope's comments come just months after he was caught up in a fake news story himself which suggested that he had endorsed Donald Trump in the US presidential race.
The false story was published on website Ending the Fed with the headline "Pope Francis shocks world, Endorses Trump for President, Releases Statement" and was shared on Facebook 960,000 times in the three months before the US election.
Pope Francis said: "I think the media have to be very clear, very transparent, and not fall into - no offence intended - the sickness of coprophilia, that is, always wanting to cover scandals, covering nasty things, even if they are true."
The Pope added that politicians use fake news to smear their rivals, particularly on social media.
He said: "[Social media platforms] have their own temptations, they can be tempted by slander, and therefore used to slander people, to smear them, this above all in the world of politics," he said.
"They can be used as means of defamation. No one has a right to do this. It is a sin and it is hurtful."