Napoli's 18-game unbeaten streak came to an end at the Bernabeu against the Champions League holders and De Laurentiis pointed the finger at Sarri for some of his choices.
Former AC Milan and Italy coach Sacchi, who had tipped Sarri's side for an upset ahead of the game, praised De Laurentiis for the job he has done since becoming Napoli's president 12 years ago but told him he stepped out of line on Wednesday.
Napoli 3 1 FT Leg 1 Game Details Live football odds with bet365. Bet Now raquo; Highlights GameCast Lineups and Stats
"De Laurentiis has done a great deal for Napoli as a director, taking them from Serie C to the Bernabeu, which is some going," Sacchi wrote in his column in La Gazzetta dello Sport. "He's invested a lot and the club have grown, even if they are not yet a top club.
"But De Laurentiis should be kinder and more prudent with some things he says. But I think De Laurentiis does really have faith in Sarri."