Mertens' goal on Saturday sent Napoli into the Coppa Italia final. It was his 122nd for the club - making him their all-time leading goalscorer.
Martinez told RTBF, "In a football world where we don't see much loyalty nowadays, I think Dries wanted to make history with Napoli and proved his love for the club.
“He is at the prime of his career, is almost considered a God in Naples, and deserves all his success."
He added: "It was an incredible match, fantastic.
“Having the opportunity to see Mertens against Romelu Lukaku in a Coppa Italia semi-final is remarkable."