(CNN) -- Anthony Bourdain doesn't believe he's naive about Iran, but what's happening there to two journalists has him stumped.
For about two weeks now, Washington Post reporter Jason Rezaian and his wife, Yeganeh Salehi -- also a journalist -- have been held in Iran on unknown charges.
Bourdain met the couple this summer while filming an upcoming episode of CNN's "Anthony Bourdain Parts Unknown."
"They were so positive about their country. I think there was just not a hint of anything that could cause anyone in any government to find fault," he said Wednesday on "Anderson Cooper 360."
"So it's just beyond me what they could possibly have done to bring this on themselves. As far as I'm concerned, they were fantastic ambassadors for a little-understood country."
Gholam-Hossein Esmaili, the director general of the Tehran Province Justice Department, has been quoted by Iran's official IRNA news agency as saying that a "Washington Post journalist has been detained for some questions and after technical investigations, the judiciary will provide details on the issue."
He did not specify on what grounds the correspondent, whom he did not name, was being held. Iranian security forces are vigilant about all kinds of enemy activities, Esmaili added, according to IRNA.
According to The Washington Post, Rezaian, 38, holds American and Iranian citizenship. He has been the paper's Tehran correspondent since 2012.
His wife, Yeganeh Salehi, is an Iranian citizen who has applied for U.S. permanent residency. She is a correspondent for the UAE-based newspaper the National, The Post reported.
Rights activists and fellow journalists have condemned the arrests of the journalists and demanded their release. According to research by the Committee to Protect Journalists, there are 35 journalists in prison in Iran.
Writing in The Post, Bourdain expressed his frustration and growing concern for the couple.
"I am, of course, deeply worried for the both of them. They seem to have dropped off the face of the Earth. No communication. No reasons given. Just gone," the host said.
"This wonderful couple is a danger to no one. They are nobody's enemy. They are without blame or malice. Why are they in jail?"
CNN's Reza Sayah contributed to this report.