The 40-year-old is currently in interim charge at Old Trafford following David Moyes' sacking last month.
Giggs started his reign with a 4-0 win over Norwich City, but United suffered another setback on home soil when losing 1-0 to Sunderland on Saturday.
Louis van Gaal is expected to take over as United manager at the end of the season, though speculation remains fierce over Giggs' involvement in the Dutchman's backroom staff.
The Welshman has enjoyed a glittering playing career at Old Trafford, including 13 Premier League titles, four FA Cups and two UEFA Champions League crowns, and has been tipped to lead United on a full-time basis in the future.
Yet Giggs concedes he may have to take the reins somewhere else in order to prepare himself for the top job at United.
He said: "I can only play for United. It's black and white, and it's not about money.
"I've been extremely lucky in that I have only ever worked at United, but I am still a young man in relative terms in management.
"I could have another 20 to 25 years in the game – and it might not all be spent at United.
"If I went elsewhere it would be strange, but I can see myself doing that.
"The association I have with United will always be special – if I have to do it I'll do it, but how it will feel I don't know."
