Mr Monti told a news conference in Rome that his predecessor's flipping back and forth between condemning the government's economic policies and praising the premier convinced him he "couldn't accept his offer".
Mr Monti declared that he would not run for office but remained available to head a future government as leader of a pro-reform coalition. Insisting Italy was better off than when he took over from Mr Berlusconi a year ago, Mr Monti said the country was at an important crossroads that required "strong shoulders and big majorities".
"If one or more political forces put forward the idea of proposing me for the post of premier, I would weigh the option," said Mr Monti, who resigned on Friday, 13 months after his non-elected government was appointed to save Italy from the eurozone debt crisis.
As senator-for-life, Mr Monti cannot officially be on the February 24-25 ballot. But Italy's electoral system does allow for him to take the job of premier if asked by the winning party.
January 11 is the cut-off date for electoral lists, which can name a 'coalition leader' even if that person is not formally a candidate. (© Daily Telegraph, London)