"We cannot call something a threat that would take nothing away from us," Monti said during a news conference with Spanish Premier Mariano Rajoy in Madrid, Italian news agency ANSA reported.
Monti leads an unelected government appointed in November after Berlusconi's resignation. Without the support of Berlusconi's People of Freedom party, Monti could lose his majority in Parliament.
Since stepping down, Berlusconi has been sentenced to prison after his conviction on accounting fraud and tax evasion.
Responding to a journalist's question, Monti said he "hadn't thought about" whether the ex-premier's threat was behind Monday's rise in the spread on Italian bond rating.
The spread rose to 355 basis points on Monday after closing Friday at 336.