"Who cares about the spread?" the 76-year-old Berlusconi, who is running for the sixth time in two decades, said in an interview with Canale 5 television -- part of his media empire.
"The spread is a trick and an invention with which they tried to bring down the majority that ruled this country," said the three-time prime minister and billionaire, referring to his last government which collapsed in November 2011 following a parliamentary revolt and panic on the markets.
The spread is the differential between Italian and benchmark German 10-year sovereign bonds -- a closely-watched measure of investor confidence.
The spread had narrowed to below 300 points last week but has widened since Berlusconi's People of Freedom (PDL) party said on Thursday that it was withdrawing its support for Monti's government.
Berlusconi then announced he would run for prime minister and Monti said he would resign as soon as parliament approves next year's budget, bringing forward the likely date for elections to February.
There is growing speculation that Monti will also decide to run in the election although he has so far declined to comment, saying only that he is not considering the option "at this stage".
The spread was around 349 points on Tuesday, while the stock market inched up 0.64 per cent in afternoon trading -- a day after it trailed other European bourses reacting to the weekend of political drama and the re-emergence of Berlusconi.
Polls say the favourite to win is centre-left leader Pier Luigi Bersani, a cigar-chomping former communist and two-time minister who spearheaded a liberalisation drive when he was in office.
Berlusconi on Tuesday also criticised Monti as "too German-centric" and said that all the main economic indicators had worsened since the former Eurocrat was installed in power.
He continued saying that Italy's record-high public debt of nearly 2.0 trillion euros ($2.6 trillion), or around 120 percent of gross domestic product, was "not as high as they want to make you think".
Monti also gave an interview to Rai public television in which he said that the government had to be "very careful" and "calm" about bond spreads.
In a rare moment of candour on his personal life, he revealed his own grandson had been nicknamed "spread" at his kindergarten and recognised the word as his own name when he heard it on television.
Monti also warned about rising populism ahead of the elections, saying: "There is a tendency to over-simplify things, to present magical solutions."
And he defended his record in governemnt saying: "We have made great progress but at a cost. In the short term, there has not been growth.
"I would appreciate it if someone could explain to me how it would have been possible financially to spare Italy from suffering the same fate as Greece and make it grow at a rapid rate," he said.
Newspaper Il Fatto Quotidiano's online edition said the contrasting interviews with Monti and Berlusconi on Tuesday were a "head-on clash".
"Each one used their own language, but this really is a challenge at a distance," the paper said.
Berlusconi also announced that only 10 per cent of the party's candidates in elections now expected in February would be chosen from current lawmakers.
Fifty per cent of the candidates will come from the business community, 20 per cent from local government and 10 per cent from the world of culture, he said, without explaining where the remaining 10 per cent would come from.
The PDL has been riven by infighting and hit by a series of fraud investigations since Berlusconi stepped down last year and retreated from the political fray before suddenly returning last week to the dismay of several dissident party members.
Berlusconi also said he would be holding talks later on Tuesday with Roberto Maroni, leader of the populist Northern League party, on forming a possible coalition.
Berlusconi's PDL and the Northern League won the last general election in 2008 but there have been tensions between the two parties in recent years.