Speaking from Tehran, Reza Saberi told RFE/RL's Radio Farda that his daughter was sentenced to eight years in prison.
He said that he was not allowed into the court, but the family's lawyer was present with the defendant to hear the verdict on April 18.
"They asked Roxana to sign the verdict, but she refused and said that she does not accept the verdict," Saberi said. "We are planning to appeal the case."
Saberi, 31, was arrested in Tehran in January.
Saberi has said she had been arrested for buying alcohol -- which is forbidden in the Islamic republic. She was then accused of working without press credentials, but was later charged with spying for the United States.
The trial began on April 13 and was held behind closed doors at a Revolutionary Court.
Reza Saberi said he still hopes the Iranian judiciary will review his daughter's case and overturn the verdict.
"I hope they will change the verdict and show some degree of fairness and justice. My daughter is innocent, but she has spent almost three months in jail," Reza Saberi said.
"They put her in jail instead of appreciating what she was doing. She came here [to Iran] to do research on Iran's history, culture, literature, and the people, but she ended up in jail."
The government has arrested several Iranian-Americans in the past few years, citing alleged attempts to overthrow its Islamic government. But they were eventually released from prison.
The United States has called for Saberi's release, dismissing the allegations against her. Secretary of State Hilary Clinton issued a statement on April 18 saying she was "deeply disappointed by the reported sentencing."
'Baseless' Accusations
Following today's verdict, the Paris-based watchdog Reporters Without Borders (RSF) "firmly" condemned the sentence, saying the conviction was "unjust."
In a recent interview with RFE/RL, RSF's Iran researcher, Reza Moini, said the accusations were "baseless."
"The truth is that no court has been able to prove the spying charges that have been brought not only against Roxana Saberi, but against a number of journalists who since 2000 have been charged with espionage," Moini said.
We believe that the charges are baseless and the way the court (trial) was held behind closed doors indicates this. Also, the fact that no evidence in the case was provided to journalists and independent observers."
Saberi has worked as a freelance reporter for several Western news organizations including the U.S. public broadcaster, National Public Radio, and the BBC.
Moini pointed out that seven journalists and two bloggers are currently in jail in Iran. Three of them -- Adnan Hassanpur, Mohammad Sadigh Kabudvand, and Mohammad Hassan Falahizadeh -- were sentenced to heavy prison terms on the same espionage charge as Saberi.
"Iran is the biggest prison for journalists in the Middle East and freedom of press does not exist in Iran," Moini said. "Journalists are in a way under a Damocles' sword of baseless accusations that have nothing to do with their journalistic activities."
U.S. Thaw
The United States severed diplomatic relations with Iran after its 1979 Islamic revolution and the hostage taking of U.S. diplomats in Iran.
Saberi's prison sentence could have a negative impact on U.S.-Iran ties. It comes as U.S. President Barack Obama has promised to engage Iran after some 30 years of strained relations.
Iranian officials have reacted by saying that they want to see a change in U.S. actions and not just words.
On April 15, President Mahmud Ahmadinejad said Iran was preparing new proposals aimed at breaking an impasse with the West over its nuclear program.
Saberi is seen by some as a victim of the reluctance by Iranian hard-liners to move towards improving relations with the United States, while others believe Tehran might want to use her as a bargaining chip for its citizens that are in U.S. detention.
RFE/RL's Radio Farda contributed to this report
Copyright (c) 2008. RFE/RL, Inc. Reprinted with the permission of Radio Free Europe/Radio Liberty, 1201 Connecticut Ave., N.W. Washington DC 20036.