Fergie saw Ferdinand slapped with a £45,000 fine for using the social networking site to respond to a comment from one of his followers claiming that Ashley Cole was a 'choc ice'.
He said: "It was almost certain to happen. The FA want to close the door on this kind of thing.
"What surprises me is that other players have been twittering for ages and have never been challenged by the FA."
Ferguson added: "Twitter; I do not understand it. I don't know why anybody can be bothered with it.
"But it is there and as a club we have given instructions to the players that they cannot talk about Manchester United.
"Rio is mature but he still has to remember that one word can make a difference - and you can't take it back."