The wiretap was of a conversation in 2005 between one of then-Prime Minister Berlusconi's political opponents, Piero Fassino, head of the former center-left Democratic Left party, and Giovanni Consorte, the former chairman of insurance association Unipol, which has ties to the Democratic Left, the Italian ANSA news agency reported.
At the time Unipol was close to taking over one of Italy's leading banks and Fassino, now mayor of Turin, was recorded as saying, "We have a bank."
The conversations were reported in Il Giornale, a conservative newspaper owned by Berlusconi's brother, Paolo Berlusconi, who was sentenced to 27 months in prison.
The court also ordered the Berlusconis to pay about $105,000 in damages to Fassino.
In Italy, prison sentences for non-violent crimes aren't enforced until the two-tier appeals system has been exhausted, ANSA said.