Napolitano said he hoped to "resolve a situation of great delicacy" with one of his country's closest allies, the Italian news agency ANSA reported.
Joseph Romano was one of 23 U.S. citizens convicted in absentia and sentenced to prison for taking part in snatching Hassan Mustafa Omar Nasr from Milan in 2003. Nasr, who was suspected of recruiting potential terrorists, was sent to Egypt for interrogation in the process known as extraordinary rendition.
The other U.S. defendants were CIA agents, including the head of the Milan station, Robert Seldon Lady.
None appeared in court in Italy.
Franco Frattini, the former Italian foreign minister, said there was little chance any of the U.S. defendants would serve any time.
Niccolo Pollari, the former head of the Italian intelligence service, told ANSA Friday he was surprised by the Court of Cassation's explanation of his 10-year sentence.
The judges said he allowed the CIA to commit a "grave violation of national sovereignty."
"In Italy, those who do their job are persecuted. Those who observe the law are condemned," he said.