Masoud Shafiei told The Associated Press that Swiss diplomats - who handle U.S. affairs in Iran - are asking that the bail be dropped or lowered for 32-year-old Sarah Shourd because they are having difficulty raising the money.
"I am aware the Swiss are making this appeal," the lawyer said. "I remain hopeful. God willing, she will be released."
Shafiei said he had no word on Iran's response and gave no indication whether he thinks the appeals will delay or further complicate Shourd's release.
Iran's judiciary granted the bail Sunday for health reasons. Shourd's mother says she has serious medical problems.
Shourd was detained along the Iraqi border in July 2009 along with two American friends, both men. Iran indicted all three on spy-related charges on Sunday which could mean trials for the two men and proceedings in absentia for Shourd if she is freed.
The families of the three claim they were innocent hikers and if they did stray across the border into Iran, it was inadvertent.
Iran's internal battles over the handling of the American woman flared again Monday. Some conservative lawmakers are objecting to any plans at freeing Shourd.
One lawmaker called it a "bonus for Quran burners" in the United States.
The political sniping has once again revealed the country's simmering political rivalries and the various groups vying for greater slices of power since last year's disputed re-election of President Mahmoud Ahmadinejad.
Ahmadinejad, who first tried to shepherd the release of Shourd last week, was rebuked by the courts who insisted that any release had to be on their terms.