On Sunday, Thunberg angered the German rail operator after she seemingly complained about having to travel in a cramped train from an eco-conference in Madrid.
A picture of her sitting on the floor surrounded by travel bags, which Greta published on Twitter, triggered a wave of criticism toward the rail operator.
In return, Deutsche Bahn published a sarcastic tweet, thanking "dear Greta" for supporting rail workers in their fight against climate change, and mentioned that Greta had a first-class ticket.
"Of course, this is not a good situation. I believe that each picture has its history. As I understand it, at first she did not have a place, but then she got it. However, she did not mention the second part of the story, probably, she knows why. Yes, to some extent, this was staged," Giffey said during a talk show organized by the Bild newspaper.
At the same time, she added that Thunberg was worthy of respect, as, despite her young age, she managed to promote her ideas.
The incident with the rail operator came just days after Thunberg was admonished by US President Donald Trump on Twitter for not working on her "anger management problem." The president's tweet followed the activist's nomination as person of the year by the Time magazine.