The nations formally recognized Libya's main opposition group, the National Transitional Council, or NTC, as the legitimate government until a new interim authority is put in place.
The declaration was made Friday in a final statement after a meeting of the so-called Contact Group on Libya.
It will keep military pressure on Gadhafi and possibly free up cash that the country's opposition needs.
The rebels, backed by NATO air force bombers, control much of the country's east, but Gadhafi controls the rest, including the capital city of Tripoli.
The Associated Press contributed to this story