Aloisi said he had not spoken to Postecoglou, his close friend and coaching mentor who refused to deny reports on Wednesday that he will resign after next month's World Cup qualifying play-off against Honduras, and was unable to shed any light on his future.
"He must have his reasons. That's all I can say," Aloisi told reporters on Thursday.
"Everyone wants to go to a World Cup as a player, as a coach, so he must have his reasons why.
"I don't know what they are, I haven't spoken to him about it.
"I spoke to him the other night before the game but it was more about the game and how we're going (at the Roar) - nothing about the World Cup.
"It's a bit of a shock. But still, we haven't heard if it's 100 per cent true or not.
"We have to respect whatever decision he makes but I'd love him to be there at the World Cup coaching the Socceroos."
Speculation is rife as to Postecoglou's motivation for leaving, with some reports claiming it is because he feels undermined or unfairly targeted by critics of his methods and his recent controversial change of formation.
Aloisi said he felt external pressure was unlikely to be the trigger.
"The criticism comes with the job, with being a coach. I'm sure he knows that's part of our role," he said.
"I don't think that's the reason why. Undermined? I don't know, that's something he has to answer."
Football Federation Australia was already on the hunt for Postecoglou's successor but didn't think it would need one until after next year's World Cup in Russia.
The big question it faces is whether it should go for an Australian coach or bring in a foreigner.
Aloisi admitted he harboured dreams of coaching the Socceroos one day and urged FFA to put their faith in another local if Postecoglou does walk away.
"I'll tell you the reason why. As a player, I really felt that putting on that jersey meant something," he said.
"And as a coach, I feel that a national team coach if he's Australian really feels something.
"Ange has shown what he's done (with) the amount of players he's brought through with the national team.
"Aaron Mooy's a prime example. He didn't play under any other coach.
"These players here, he's actually given them an opportunity because he's believed in them from watching them in the A-League.
"I don't think a foreign coach, (like) we've had in the past, believes in what we're doing here in Australia."