The retired striker legend took offence to the 71-year-old manager's statement, as he compared him to the current Real Madrid star, saying that it was disrespectful
The Scot described Ronaldo as the "old and fat one" when asked to compare the 36-year-old to his namesake Cristano ahead of the Spanish giants' visit to Old Trafford on Tuesday.
But, when quizzed about the Glaswegian's disparaging remarks during a Fifa visit to Arena Pernambuco, one of the venues for the World Cup 2014, Ronaldo remained diplomatic.
"I respect his opinions, I'm not pretentious as to expect that everyone will think I'm the best," he told reporters.
"I'm happy for what I achieved in football and for having been chosen as the best in the world.
"I feel sorry for the disrespectful manner in which he referred to me, it's something that's not good for someone of his position."
The 36-year-old was widely revered for his impact on the footballing world, with the Brazilian scoring over 400 goals during a glittered career that saw him win the World Cup twice and earn the accolade of Fifa World Player of the Year on three separate occasions.
Recently, the striker's legacy has been sullied by his well-documented weight issues. The former Golden Boot winner turned to reality TV and lost more than four stone throughout the course of the Brazilian show - a staggering feat that he jokingly claimed Ferguson was unaware of.
"About my former figure, I have nothing add." he said.
"He clearly hasn't seen me since 'Medida Certa' [the show]."