Cook faced the media for the first time since reports emerged that team director Andy Flower was prepared to move forward without Pietersen.
While Cook's appearance was ostensibly to preview the start of the one-day international series in Melbourne on Sunday, the fall-out from the 5-0 Ashes whitewash again took centre stage.
Pietersen's future is the lead act in that narrative, but Cook was unwilling to disclose any information on what might be the next chapter in what is already looming as a sorry saga.
In addition to being questioned about Pietersen's future, Cook was probed for closer information regarding the right-hander's attitude in the dressing room to his own relationship with him.
"It's very hard for me to talk to you the media about this. It's very hard," the 29-year-old skipper said.
"I can't do that. Confidentiality and stuff like that - what happens in the dressing room stays in the dressing room.
"I refuse to do that."
Asked if that could be construed as a failure to endorse Pietersen, he replied: "You can regard it as you want. As the way with the media that happens."
Cook was not always defiant, though - cracking jokes at times to lighten the mood - but he admits the failings of his side in the Ashes have weighed heavily on his shoulders in the week since the whitewash was confirmed in Sydney.
"Obviously when you lose a series 5-0 a lot of things get thrown up and thrown in your face as a captain," he said.
"You start looking at everything and it is important that we do that.
"What is also important is that it has only been a week since everything happened.
"I would be wrong if I wasn't lying in my bed over the last week or so thinking about stuff I would like to do and how I would like to lead this side forward and the decisions which go with that."
Any decision over Pietersen's future, or on the other England players who struggled Down Under, will not be made until Cook returns home after the conclusion of the five-match ODI series on January 26.
The skipper is then set to meet with Flower and the England and Wales Cricket Board (ECB) to begin their series review.
Cook has already this week met with new ECB managing director Paul Downton, while he also spoke with Flower before he flew home from Sydney.
While Cook is fully aware of the importance of those pending discussions, he is determined to push them to the back of his mind for now as he plots a way to win the upcoming 50-over series against Australia.
"What is important for me is the one-day series at this precise moment in time," he said.
"We know that when I get home from this one-day series a lot of important decisions on how we want to go forward with this Test team, the one-day team and my future - all that kind of stuff - is very important."
The relevance of the ODI series is accentuated by the fact that the same grounds will host the World Cup in just over a year's time.
"My total focus has to be on us winning games of cricket in this series," he added.
"We have a World Cup in 2015 in exactly the same conditions as we are going to experience here and that has to be given my full thought.
"After this series then you go back on to how do we rebuild the Test side."
Cook will almost certainly be the man at the helm when that rebuild begins, with the left-hander having been given a vote of confidence by the ECB.
"That is reassuring. It is nice knowing that," he said.
"It is nice knowing that you have the opportunity to try and make amends as a captain.
"I'm desperate to try and do it. The challenge is whether I'm good enough to do it.
"We're going to see over the next couple of years or however long."