USA Basketball said Green, of the Oklahoma City Thunder, and the Washington Wizards' McGee were among the casualties in the run-up to the 2010 FIBA World Championships in Turkey.
One more player must be cut to reach the official roster of 12 players for the Aug. 28-Sept. 12 event.
"It's always difficult to have to pare down and make these decisions because each of these young men have given their time and energy to be part of USA Basketball," USA Basketball Chairman Jerry Colangelo said.
Colangelo said the decision made was predicated on having fewer players to work with and play during upcoming exhibition games.
Team USA was set to play an exhibition game Sunday in New York against France, with the 13 finalists then traveling to Madrid for practice sessions.