Armitage has been ignored by the national team setup since his move to Toulon in 2011 due to England's policy of not selecting players who play their club rugby overseas.
The flanker's sensational form in France has seen him win the European Player of the Year award and help Toulon to consecutive Heineken Cup successes, but Lancaster insists that he will only be considered should his squad be struck by a number of injuries.
"The special circumstances have got to be associated with injuries. It's not my rule but it is a rule I support," Lancaster is quoted as saying by PA.
"The players are aware: I had a conversation with Toby Flood about his move to Toulouse this summer and he's aware of his position. But equally there is that potential there, but it would be more likely closer to a World Cup if that was the case.
"That would have to be for me close to a World Cup, I wouldn't do it at the moment, for a New Zealand tour, autumn international or for Six Nations either. Not when I've got other players out there who could be developed."
Armitage has won just five caps for his country since making his debut in 2009.