The sentence imposed on Sakineh Mohammadi Ashtiani had caused an international outcry but judiciary official Malekajdar Sharifi said that had not influenced the decision and it might still carry out the sentence later.
"The verdict is definitive and applicable. But it has been halted due to humanitarian reservations and based on the judiciary chief's order," said Sharifi, the senior judiciary official in Eastern Azerbaijan province, where she was sentenced.
"The sentence will not be carried out for the time being."
However, Mohammadi Ashtiani, who will remain in prison, could still face execution, IRNA quoted the official as saying.
"Despite protests from the West, her sentence will be carried out if the judiciary decides to carry it out," Sharifi said.
Murder, adultery, rape, armed robbery, apostasy and drug trafficking are all punishable by death under Iran's sharia law, enforced since the 1979 Islamic revolution.
Human rights group Amnesty International said last week it feared that Mohammadi Ashtiani, who has two children, could be executed by stoning at any time for adultery. The United States, the European Union, Britain and international human rights groups all appealed for a stay of execution.
Amnesty said she was convicted in 2006 of having an "illicit relationship" with two men and received 99 lashes as her sentence.
The rights group said that, despite this, Mohammadi Ashtiani was subsequently convicted of "adultery while being married," which it said she denied, and was sentenced to death by stoning.
Amnesty said it was aware of at least 10 other people, including seven women, under sentence of stoning in the Islamic state.
Mohammad Javad Larijani, secretary-general of the Iranian high council for human rights, said on Friday that Mohammadi Ashtiani's case was being reviewed by the judiciary.
IRNA quoted the judiciary official as saying: "Mohammadi Ashtiani has committed various and very serious crimes, and not only adultery."
Amnesty International lists Iran as the world's second most prolific executioner in 2008 after China, and says it put to death at least 346 people in 2008.
The Iranian authorities routinely dismiss charges of rights abuses, saying they are following Sharia.
