Andrew Chan and Myuran Sukumaran have been on death row since 2006 for organising to smuggle heroin out of Bali with seven other Australians.
Lawyers for the men said they were planning to lodge an administrative appeal against Indonesian president Joko Widodo's refusal to grant them pardons.
They said the president should have considered each case and not just refused clemency for all drug crimes, as he is doing.
But Indonesian attorney-general Muhammad Prasetyo has dismissed the attempt at another legal challenge, saying it is not possible to challenge the president.
"Clemency is a prerogative right that cannot be obstructed by anybody, can not be challenged by anybody. It's a prerogative right," Mr Prasetyo said.
"The president has that prerogative right as the head of state and nothing can obstruct that.
"In this republic he's the sole holder of that right. Clemency, amnesty, abolition, rehabilitation, as the constitution stipulates. Only the president has the authority.
"The legal process is completed. The legal venues that we have are through the court procedures, higher court appeal, Supreme Court appeal, judicial review and the last venue is clemency. Clemency is a special legal venue."
But all efforts to influence Mr Widodo have so far failed, including emotional pleas from Chan and Sukumaran's families, and Prime Minister Tony Abbott asking if there was anything that could be done to spare the men.
We have to respect Indonesia's sovereignty: Bishop
Foreign Minister Julie Bishop was asked about the case on commercial television last night.
"The fact is, drug trafficking is a crime in Indonesia that attracts the death penalty and we have to respect Indonesia's sovereignty, it's an independent nation state with its own judicial system," Ms Bishop said.
On Monday, Sukumaran's mother Raji said she blamed the Australian Federal Police for her son facing now death.
It was the AFP that tipped off Indonesian police about the Bali Nine's plans, meaning the men were arrested there and charged under Indonesian law.
Mr Prasetyo has now confirmed the executions will be done, as expected, at a maximum security prison facility on Nusa Kambangan, an island off Java. But there is still no word on when the executions will be carried out.
"I'm telling you, we haven't decided on the time, we have decided the location. The location will be in Nusa Kambangan," he said.
Nusa Kambangan is a high security island prison, where the men would be tied to a pole and shot by firing squad.
While Indonesia informed the Australian embassy last week that it planned to execute Chan and Sukumaran this month, Indonesia's justice and human rights minister Yasonna Laoly said their executions could be delayed by a pressing political situation, involving a war of sorts between corruption investigators and the national police.
But Mr Prasetyo said that would not affect plans to execute the Australians.
A senior government source doubts the executions will be carried out this week or next, but it is up to the attorney-general.
Once the logistics are organised Mr Prasetyo only has to give 72 hours notice that the men are to face the firing squad.
By Indonesia correspondent George Roberts