Ferguson: Giggs unlikely to return for Wales
"You must be joking," Ferguson told a news conference on Friday. "I can't see it, it must have been a weak moment for Ryan. I can't see that happening."
Giggs, who retired from international football in May 2007, raised hopes of a Welsh return and a future Euro 2012 match-up against group opponents England when he said he would consider a comeback.
"I wouldn't dismiss the idea. If I had that call from (Wales coach) John (Toshack) I would have to think hard about it. I wouldn't rule it out," Giggs told the Western Mail newspaper before later clarifying any call-up would have to be in an emergency.
Giggs, who represented England at schoolboy level, has 64 caps for Wales and is widely regarded as one of his country's finest ever players.
Giggs has won 11 Premier League titles with United and two Champions League trophies, but has tasted no international success as Wales last qualified for a major international tournament in 1958.
Wales start their Euro 2012 qualifying campaign in Montenegro on Sept. 3 before October matches at home to Bulgaria and away to Switzerland. They host England on March 26, 2011.