(Reuters) -- Ahmad Sheikhzadeh, an Iran-born U.S. citizen, was sentenced to three months on Friday for evading taxes by concealing his income and helping family and friends make money transfers that violated U.S. sanctions against Iran.

"The accusations against him are unacceptable and baseless," Iranian foreign ministry spokesman Bahram Qasemi said in a weekly news conference broadcast live on state television.

"This verdict was politically motivated as the Americans are constantly engaging in psychological warfare against Iran."

Qasemi called on Washington to stop its "continuous pressure" on Iranians in the United States and other countries.

"The Americans should reverse this wrongful policy and release all Iranian detainees immediately," Qasemi added.

An Iranian judicial official said last year more than 56 Iranians were imprisoned in the United States, most of them for violating U.S. sanctions against Tehran.

Iran holds at least seven American citizens and permanent residents in jail.

(FILE PHOTO - Ahmad Sheikhzadeh (C), a consultant to the Iranian mission to the United Nation, leaves Brooklyn Federal Court in New York, March 23, 2016. REUTERS/Pearl Gabel/File Photo)