Louis van Gaal remains the favourite to succeed David Moyes as United manager, and reports emerged from Holland last week claiming the Dutchman wanted to bring Keane into his backroom staff at Old Trafford.
Van Gaal has immense respect for Keane from his first stint as Holland coach, when the former United captain proved pivotal in the Republic of Ireland's 1-0 win over Holland in a 2001 World Cup qualifier at Lansdowne Road.
But, speaking at the launch in Cork of "Shades Week", in aid of the Irish Guide Dogs For the Blind, Republic of Ireland assistant Keane said: "I’ve got a job already and I’m very happy with that job. No, I’ve never even thought about the Manchester United job.
"I probably won’t ever speak to Alex Ferguson again in my life. He’s not on my mind at the moment. I wouldn’t be losing sleep over it or anything like that. Have I mellowed at all? No, I’m not sure about that."
Ferguson now occupies an ambassadorial role at United and is likely to be consulted during the club's search for a new manager, although the final decision will be left to executive vice-chairman Ed Woodward.
Keane and Ferguson's relationship ended spectacularly in 2005 when the former captain was sacked by the Scot following an unaired, but brutal, analysis of the team's 4-1 defeat away at Middlesbrough on MUTV.
Ferguson said Keane was "frightening to watch" during a team meeting and admitted to being left "upset" by his behaviour.
Old wounds were reopened when United considered suing Keane in 2008 and when Ferguson dismissively described him as a "TV critic" in the aftermath of a humbling 2-1 Champions League loss at Basel three years later.