The track near Milan in northern Italy has hosted every Italian Grand Prix since 1950 except 1980, but the F1 supremo is growing increasingly concerned about the viability of it hosting the event.
Monza has two years left on its contract with the FIA, and it appears organisers will have to do a lot to make the 83-year-old alter his view.
Reports that Mugello, a track used in MotoGP, could become the new host of the race were rejected by Ecclestone but he was adamant changes would need to be made in the future.
"It's not good. I do not think we'll do another contract (with Monza)," he told the Gazzetta dello Sport. "The old one was a disaster for us from a commercial point of view.
"So it's bye-bye after 2016."
A drop in performance from Ferrari has seen the Italian constructors win only once in the past seven years at Monza, and Ecclestone cited that as one of the reasons for his concerns.
"Audiences are lower in Italy than elsewhere," he added. "If Ferrari started to end up first and second in qualifying and races the audiences would improve everywhere.
"Ferrari is a worldwide passion."