Levein, who named no players from the Ibrox club in Monday's squad announcement for the friendly against Australia, admitted it would be harder for individuals to stake a claim for a place in future squads, but did not rule it out completely.
"Lee Wallace is a good example and I wouldn't close the door on him at all," Levein said. "The best scenario is for players to be playing at the top level to play international football. It makes it so much easier to step from one to the other."
Levein also revealed Scotland captain Darren Fletcher will meet up with the squad and train with them ahead of the fixture at Easter Road next Wednesday.
The Manchester United midfielder's career was seemingly in the balance when Red Devils manager Sir Alex Ferguson revealed last month that the 28-year-old was yet to return to training following a long-standing chronic bowel complaint.
But Levein confirmed that Fletcher is now on his way back to playing competitive football for the first time since a Champions League tie against Benfica at Old Trafford in November.
He said: "Darren will be with us at the weekend, he is back in training and he played 45 minutes in a practice match last week.
"He is not in the squad because he has not played for Manchester United but he will come back and do a bit of training with us."
He added: "We will see how he gets on between now and September and I think you'll guess that if he is fit he will be in the team."