Ronaldo swapped Real Madrid for Juve in a blockbuster €112 million (£102m/$124m) deal ahead of the 2018-19 season, however, there was apparent interest from Milan prior to the transfer.
Ex-sporting director Massimiliano Mirabelli claimed Ronaldo was on the brink of signing for Milan before the former ownership – led by Li Yonghong – blocked the deal prior to hedge fund Elliott Management assuming control of the Italian team.
And Fassone, who followed Mirabelli out of Milan following the takeover in July last year, backed up those claims.
"The president wanted Cristiano Ronaldo, but the figures told us this was inadvisable," Fassone told Sportitalia.
"Ronaldo was open to evaluating the opportunity, as Milan are a famous club and there was enthusiasm around us.
"However, we never went beyond some internal calculations and seeing if he was potentially open to it."
The former ownership group oversaw a period of big spending, with Leonardo Bonucci's shock €42m arrival from Juve headlining a 2017-18 window which also included the signings of Andre Silva, Hakan Calhanoglu, Andrea Conti, Mateo Musacchio, Ricardo Rodriguez, Lucas Biglia, Franck Kessie, Nikola Kalinic and Fabio Borini.
Bonucci only spent one season in Milan before the Italy defender returned to Turin and Fassone admitted the deal was ill-advised.
"Bonucci was a mistake," Fassone said.
"When we signed Bonucci from Juventus, we'd already made eight or nine buys. The strategy was to create a squad suited to 4-3-3, so we already had the defenders and really didn't need another. What we were missing was a centre-forward, for whom we had €70m set aside.
"The choice we made in the end was to reduce the budget for the striker and sign a leader for the dressing room. With hindsight, if we had just invested in a top forward as was the plan, it would've gone differently."
"Pierre-Emerick Aubameyang was a target, as Mirabelli was always a fan," Fassone said. "However, it's complicated to deal with German clubs. The demands were higher than his real value on the market."
Milan are preparing for the 2019-20 season under new head coach Marco Giampaolo after Gennaro Gattuso stepped down following the club's fifth-place finish last term.