"There is no commercial transaction (between Iran and Turkey) that is against national and international law," Bozdag was quoted as saying by aa.com.tr.
An indictment was announced Sept. 6 in New York charging former economy minister Zafer Caglayan and three other Turkish nationals with violating US sanctions against Iran.
The charges stem from a probe into Reza Zarrab, a Turkish-Iranian gold trader arrested in the US last year for alleged sanctions evasion.
Bozdag said Caglayan protected Turkey's interests and did his duty according to national and international laws.
"There is a very different thing here…It is part of a very dirty game. There is no evidence; there are fabrications," he said.
The Iranian-born Zarrab was arrested on March 21 last year in the US on fraud and Iran sanctions-related charges.
He earlier faced an investigation in Turkey in 2013 on charges of alleged illegal gold sales to Iran via Turkey, which led to his detention. That case was dismissed in 2014.