She was initially sentenced to death by stoning, but the execution was put on hold earlier this month after an international outcry.
Malekadjar Sharifi, an Iranian official in Eastern Azerbaijan province, was quoted as saying the suspension was not influenced by the international condemnation drawn by the death sentence.
Although she will not be stoned, rights groups worry that Ashtiani could still be hanged.
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.
At least 10 other people, including seven women, are under sentence of stoning in the Iranian jails, Amnesty said.
Protest organisers hope continued international pressure will force the Iranian government to free Ashtiani.
"We are hoping this will be a stepping tone to ending stoning and executions in Iran once and for all," Namazie said.