Ciro Esposito, 29, was shot in the chest ahead of Napoli’s Coppa Italia final win against Fiorentina in Rome on May 3.
Esposito had been in a critical condition in hospital but died on Wednesday, with De Laurentiis revealing his sorrow for the loss.
"We are really sad about Ciro Esposito. Really sad for his family, for his mother, for himself," De Laurentiis said.
"We all hoped for a miracle. This highlights once again the problem of safety in this sport.
"Football is a sport and it can't be a violent place where you go and risk your life. It can't be a place where you can jeopardise relationships among Italian people."
The Napoli owner said Esposito’s death exemplified the importance of Italians uniting to avoid any similar tragic incidents occurring in the future.
"I think we tend to forget that we are in Italy. We aren't in Naples, Turin, Milan, Genoa, Florence and so on," he said.
"Otherwise, it means that we have gone back to the municipalities of the 1200s.
"I understand that we are a very young country, but perhaps we haven't been able to teach enough how to be Italians and the value of being Italians and this 'shabby' approach of ours eventually leads us to minimising the importance of being Italians.
"The famous 'Made in Italy' is a value but if we keep treading on it, we just keep scoring own goals."