Dallas, 25, has returned to Elland Road because of a calf injury.
The former Brentford player, who represented Michael O’Neill’s side at Euro 2016, was injured during his national side’s 4-0 win over San Marino last month.
Dallas hasn’t played since, during which time United have marched up the Championship table to sixth place, following Saturday’s memorable 3-2 win at Norwich City.
He was last week named in the squad for the matches against Azerbaijan and a friendly against Croatia, but Whites boss Garry Monk said last week he hoped “common sense” would prevail and Dallas would not be chosen to play.
Monk said: “It’s been four weeks and Stuart has not even touched a football,” said Monk.
“From a medical point of view, from a physical point of view, from any point of view, it makes no sense and it puts the player at a high risk if you play the minutes.
“But with the international team you don’t tell them what to do, they work the way they work and they have their prerogative, but common sense I’m sure will prevail.
“It’s impossible for a player to go four weeks without even kicking a football to then go into an international game with a high level.
“It’s a very high risk and I’m sure Northern Ireland don’t want to risk that and we don’t Stuart to be risked like that.”
Monk added: “He’s not back in training so it will be four weeks and he is due to start training on Monday. But of course the international call up is their prerogative and their right to have an assessment of the player.”