Ciro Esposito, 29, was shot in the chest ahead of the clash between Napoli and Fiorentina at Rome's Olympic Stadium on May 3.
He had been in a critical condition in hospital, with his death announced on Wednesday.
"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."
De Laurentiis said the incident reflected growing concerns about the disunity among Italian regions.
"I think we tend to forget that we are in Italy. We aren't in Naples, Turin, Milan, Genoa, Florence and so on," he added.
"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 minimize the importance of being Italians.
"The famous 'Made in Italy' is an added value but if we keep treading on it, we just keep scoring own goals."
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