"We have to send a signal that the euro is irreversible," Padoan told the weekly magazine l'Espresso in an interview when asked about Greece's situation.
"If a country were to leave, it wouldn't just mean one less country in the union but the transformation of the euro into a mechanism that can be undone."
His words contrast with those of some economists and politicians who have played down the likely impact of a Greek exit on the rest of the currency bloc.
Padoan said Italy supported Greece's efforts to transform its economy with a medium-term program of structural reforms.
(Reporting By Gavin Jones; editing by Steve Scherer)
