Verratti's agent made the claim of a Napoli offer this week.
"Some media, at times, need to write something and report things which haven't been verified with the source," De Laurentiis tweeted.
"Verratti is not for sale. Agents, through the media, are trying to put pressure on PSG in order to get the player an increased salary.
"We are friends of PSG and we are not taking part in this game."