The Scot makes the revelation in Alex Ferguson, My Autobiography, which was launched at a press conference on Tuesday in London.
Ferguson is typically forthright in the book, to be officially published on October 24, criticising several former players including Roy Keane and David Beckham.
The 71-year-old, who retired last summer after 26 years in charge at United, said the Football Association approached him twice to take over as England manager.
The first time was in 1999, before Kevin Keegan was given the job, and the second in 2001 before Sven Goran Eriksson took over.
"(Adam) Crozier made me the offer to manage the team," Ferguson says.
"It didn't take me long to decide, 10 seconds. There was no way in a million years I could manage England.
"Imagine me going back to Scotland after that, dearie me. Of England, it was a great opportunity to relegate them."
Ferguson, who managed Aberdeen and Scotland in the 1986 World Cup finals, does not hold back from criticising some of his former players.
His former captain Keane is particularly targeted, with Ferguson saying that the Irishman became a liability when he began to lose his dominance in midfield toward the end of his career.
"The hardest part of Roy's body is his tongue," Ferguson writes.
"It was frightening to watch. And I'm from Glasgow."
Ferguson says Beckham was more interested in his fame than his football towards the end of his career and also confirms that Wayne Rooney did indeed ask for a transfer, before later retracting his request.
The Scot also used the book to lay into some of his rivals, including former Liverpool manager Rafael Benitez.
In the book, he says Liverpool captain Steven Gerrard was no match for his own midfielders Keane and Paul Scholes, and describes Chelsea's Frank Lampard as "not an elite international footballer".
KEY QUOTES FROM SIR ALEX FERGUSON'S AUTOBIOGRAPHY:
On former Manchester United midfielder David Beckham:
"David was the only player I managed who chose to be famous, who made it his mission to be known outside the game."
On former United captain Roy Keane:
"He has the most savage tongue you can imagine. He can debilitate the most confident person in the world in seconds with that tongue."
On Chelsea striker Fernando Torres:
"Torres was blessed with great cunning: a shrewdness that was borderline Machiavellian. He had a touch of evil, though not in the physical sense."
On Liverpool captain Steven Gerrard:
"I am one of the few who felt Gerrard was not a top player."
On former Manchester United goalkeeper Mark Bosnich:
"A terrible professional ... we played down at Wimbledon in February (2000), and Bosnich was tucking into everything: sandwiches, soups, steaks. He was going through the menu, eating like a horse."
On Chelsea midfielder Frank Lampard:
"I didn't think of him as an elite international footballer."
On Napoli coach Rafa Benitez, previously of Liverpool and Chelsea:
"The mistake he made was to turn our rivalry personal ... I had success on my side."
On player power:
"In modern football, celebrity status overrides the manager's power. In my day you wouldn't whisper a word about your manager. You would fear certain death. In my later years, I would hear constantly about players using their power against managers, and the player receiving the support of the public and even the club."
Recalling what a un-named senior Inter Milan official told him:
"Do you know the difference between the English and Italians? In England they don't think a game can ever be corrupt. In Italy they don't think a game cannot be corrupt."
On former US President John F Kennedy:
"I developed a forensic interest in how he was killed, by whom and why."