The 23-year-old recently admitted he would welcome a move to AC Milan, one of the clubs reportedly keen to sign him this summer.
"The indecent proposal I referred to (earlier this month) would be of 100million euros," said De Laurentiis in a press conference.
"Otherwise, Hamsik will remain here."
Hamsik, who joined Napoli from Brescia in 2007, is under contract with the Serie A outfit for another four years.
He scored 11 goals in 37 league appearances to help the Naples outfit finish third last season and qualify for the Champions League.