The 21-year-old failed to report for the Garry Lynch Memorial friendly between Junior side Cambuslang Rangers and an Ibrox reserve team on August 11.
The no-show prompted an angry response from manager Ally McCoist, who has told the player to keep his distance from the club's Murray Park training complex for the time being. Cole's last Rangers appearance was in a friendly against Elgin City in July.
"Darren failed to report for the game against Cambuslang," said McCoist, "but he's not following a fixed suspension. He didn't attempt to contact anybody to let them know he wouldn't be coming and it goes without saying we thought his conduct was totally unacceptable."