Press video footage showed Roth, who has consistently criticized Iran's treatment of women, giving a high-five to Iranian ambassador Ali Reza Sheik Attar as she made her way to her seat at last weekend's international security conference.
In an incident lasting all of four seconds, Attar surprised Roth by raising his hand in the friendly, typically American gesture, which she returned with gusto and without hesitation.
Since being appointed Iranian ambassador to Germany in 2008, Attar has been busy deflecting criticism of Iran's human rights record, often from Roth herself.
The bizarre exchange was captured on film by Reuters news agency and used as a filler in a piece on the discussion about Iran's nuclear program. But once the exchange was spotted, Roth came under growing pressure to explain herself and received a slamming from the press, as the images circulated on social networks over the weekend.
The accusation was that Roth was friends with, and shared approving, grinning gestures with a man who had had opponents hanged when he was a governor of Kurdistan in the 1980's.
But the ambassador also found himself in an awkward position - his beliefs do not permit him to shake hands with a woman, but he felt he should acknowledge Roth.
“The ambassador of the Islamic Republic of Iran never shakes hands with a woman, and he has never shaken Claudia Roth's hand either,” a spokesman told the Süddeutsche Zeitung on Friday. The ambassador had attempted a polite greeting, without having to actually shake Roth's hand, he suggested.
“Completely surprised by this unexpected gesture,” Claudia Roth responded with a “quick touch of the ambassador's hand,” said the spokesman.
Roth had meant to be polite, he said, as she was in the middle of ultimately unsuccessful negotiations with the diplomat to lift the travel ban on Iranian filmmaker Jafar Panahi. The banned director, who is under house arrest in Iran, had hoped to travel to the Berlinale film festival for the premiere of his film Pardé (Closed Curtain) on Tuesday.