The White House has expressed dismay after Iran jailed a journalist for eight years on spying charges.
Roxana Saberi, 31, was sentenced after a brief trial held behind closed doors. The trial began on Monday. No evidence was made public.
She has been held in prison in Tehran since January.
Ms Saberi, who has American and Iranian nationality, has worked for the BBC, Radio New Zealand and NPR Radio and Fox News in the United States.
She denies the charge and her father says she will appeal and go on a hunger strike.
Ms Saberi originally faced an accusation of buying alcohol, and later of working as a journalist without a valid press card. The charge of spying was introduced two weeks ago.
The verdict came despite calls by the Obama administration for Ms Saberi's release and diplomatic overtures to Iran after three decades of severed ties.
A spokesperson for the White House Robert Gibbs says President Barack Obama is "deeply disappointed at this news" and has expressed his concern.
US Secretary of State Hillary Clinton earlier expressed her disappointment at the sentence.
She said the US would vigorously raise its concerns about the case with Tehran.
Washington, which has no diplomatic ties with Iran, was working with Swiss diplomats in Tehran to obtain details about the court's decision and ensure Ms Saberi's well-being, she said.
The BBC reports Ms Saberi has spent six years in Iran studying and writing a book.
The daughter of an Iranian father and a Japanese mother, she holds two master's degrees and is currently studying for a third.