Washington-The United States has said that it was “troubled” by Iran’s 18-year sentence of an American citizen as the State Department urged Tehran to cease arbitrary detentions.

“We are troubled by reports that Robin or Reza Shahini, a person reported to be a U.S. citizen, may have been convicted and sentenced to 18 years in prison,” State Department spokesman John Kirby said Tuesday.

“We reaffirm our calls on Iran to respect and protect human rights and fundamental freedoms, cease arbitrary and politically motivated detentions, and ensure fair and transparent judicial proceedings in all criminal prosecutions consistent with its laws and its international obligations,” he said.

Kirby stressed that Washington holds onto its policy of not paying any ransom for prisoners.

“We don’t pay ransom. We didn’t then, we don’t now, we’re not going to change that policy going forward. And we’re going to continue to raise our concerns with Iranian officials about the detained citizens there,” he said.

“That’s not going to stop. We’re also going to continue to call on Iran to respect and protect human rights and to ensure fair and transparent judicial proceedings,” the spokesman added.

The sentence against Shahini comes after an Iranian American businessman and his 80-year-old father were sentenced last week to 10 years in an Iranian prison.

Siamak Namazi and his father Baquer Namazi were sentenced for collaboration with the American government.

Shahini, 45, immigrated to the U.S. in 2000 and resided in the California city of San Diego. He received the citizenship in 2009.

The San Diego man said he was arrested July 11 when he was visiting his mother and other family members in Iran.

State Department sources told Asharq Al-Awsat that contacts are underway between Washington and Tehran to resolve Shahini’s case.

Analysts said that the long sentences against U.S. citizens of Iranian origin could harm ties between the two countries.

Iran is seeking to pressure Washington to receive ransom, they added.