Ronaldo returns to Old Trafford on Tuesday as Real Madrid take on United in the second leg of their last 16 UEFA Champions League tie.
The Portuguese star's future has been the subject of speculation for the last few weeks as talks over a new deal at the Bernabeu have dragged on.
Although Ferguson has previosuly admitted he would love to see Ronaldo back at Old Trafford he has dismissed talk that a move could be on the cards this summer.
"There hasn't been anything to encourage me to think Cristiano would come back here," said Ferguson.
"As far as I am aware, there is nothing in it at all. Ronaldo has got two years left on his contract and it seems to me it is all part of the negotiations that are going on about a new deal.
"Maybe his agent is playing the game. I think it is false hope. Cristiano will get a good reception. All our former players, especially the ones who have been great for this club, get a good reception when they return."
Ferguson believes Ronaldo is at the peak of his career and he has joked he has two ways to try and stop the forward ending their Champions League dreams.
"He is a better player now than he was when he was with us because he has matured," added Ferguson. "He is 28 and at the peak of his career. From 28 to 32, with the fitness Ronaldo has got - he never misses a game and is never injured - he will be at his absolute best," he continued.
"I've got a plan to stop him: it's called a machete. Plan B is a machine gun!"