President Obama said he's "gravely concerned" about the safety and well-being of jailed U.S. journalist Roxana Saberi and is calling for her release from an Iranian prison.

At the Summit of the Americas, Obama said Sunday that he's working to ensure the safety of Saberi, a 31-year-old dual American-Iranian citizen. She was sentenced to eight years in an Iranian prison on charges of spying for the United States.

"She is an American citizen and I have complete confidence that she was not engaging in any sort of espionage," Obama said. "She is an Iranian American who was interested in the country which her family came from. And it is appropriate for her to be treated as such and to be released."

Meanwhile, President Mahmoud Ahmadinejad said Saberi should be allowed to offer a full defense during her appeal, the state news agency reported Sunday.

The statement came a day after Iran announced the conviction and sentence for Saberi. It was the first time Iran has found an American journalist guilty of espionage and her lawyer said he will appeal.

"Prepare for the court proceedings ... to observe and apply justice precisely," the IRNA state news agency quoted Ahmadinejad as saying. He instructed chief Tehran prosecutor Saeed Mortazavi to personally ensure that "suspects be given all their rights to defend themselves" against the charges.

Saberi's case has been an irritant in U.S.-Iran relations at a time when President Barack Obama is offering to start a dialogue. A few days before Saberi's sentence was announced, Ahmadinejad gave the clearest signal yet that Iran too was willing to start a new relationship with the U.S.

The White House said Saturday that Obama was "deeply disappointed" by Saberi's conviction. The U.S. has called the charges against her baseless, and the State Department said Iran would gain U.S. good will if it "responded in a positive way" to the case.

Saberi's father said his daughter was not allowed a proper defense during her one-day trial behind closed doors a week ago. He also said she was tricked into making incriminating statements by officials who told her they would free her if she did.

Saberi was arrested in late January and initially accused of working without press credentials. But earlier this month, an Iranian judge leveled a far more serious allegation, charging her with spying for the United States.

The Fargo, North Dakota native had been living in Iran for six years and had worked as a freelance reporter for several news organizations including National Public Radio and the British Broadcasting Corp.

The Associated Press contributed to this report.