Ghasemi said White has not been abused or mistreated, calling the former prisoner's allegations "psychological warfare", according to the AP.
"The case of this person is being handled by the relevant authorities and at the conclusion of this process they will issue the necessary information", Ghasemi was further quoted as saying on his Telegram account.
"Michael White was arrested in the city of Mashhad a while ago, and within a few days after his arrest the United States government was informed of the arrest through the Swiss Embassy in Tehran", ministry spokesman Bahram Ghasemi said.
Ghasemi said the USA government, through the Swiss embassy in Tehran, was informed of the arrest during the early days of the incident.
Among them is Xiyue Wang, a Princeton University student, who was given a 10-year sentence for espionage.
White joins at least three other USA citizens, two of them of Iranian descent, being held in Iran.
She said the State Department had not contacted her and she was unaware he was in prison until reached by CNN. "We have no higher priority than the safety and security of USA citizens overseas".
Siamak Namazi, and his father, Baquer Namazi, are Iranian-Americans who have been detained since October 2015 and February 2016, respectively. White at Iran's Vakilabad Prison in the city of Mashhad. While the Trump administration offered to discuss prisoners past year, a senior administrative official said Iran turned that offer down, leaving the fate of the Americans unclear.
His family say he suffers from acute asthma and shortly before his latest visit he underwent chemotherapy for a neck tumour. About five months later, the State Department informed her that he's being held in an Iranian prison.
Tensions have been high since U.S. President Donald Trump pulled Washington out of a landmark nuclear deal with Iran and reimposed crippling economic sanctions against Tehran a year ago. In the piece, Irvar Farhadi, a former Iranian prisoner, said he met Mr.
Several Americans have been detained in Iran in recent years and Mr Trump warned in 2017 that Tehran would face "new and serious consequences" unless all unjustly held U.S. citizens were freed.