"There is a fleeting moment of a simulation of cannibalism from a film clip. It's a sensational representation which lasts about 20 seconds, but it's quite clearly not a real moment," he said.
A sign at the entrance to the gallery warns that the exhibition contains "images of simulated violence".
"We don't seek to cause offence but, historically, some people have always had a strong reaction to contemporary art," Mr Kreisler said.
"That is the nature of art and we get such a diverse range of people bringing a range of beliefs and experience to the gallery. Sometimes it's a case of 'What are you bringing to the art experience?"'
About 4000 people visited the DPAG a week, he said.
"It's not a show that's trying to create sensationalism. People see much more graphic images on their TVs and PCs every day. It's educational. It's a very significant exhibition by one of the most significant German artists.
"The Otago Museum has artefacts on display which were actually used in cannibalism. So, anyone wanting to see something really graphic could go and have a look there."
University of Otago theatre and performing arts studies lecturer Dr Jonathan Marshall will hold a talk on the exhibition at 3pm in the gallery on Sunday.
The exhibition will finish on October 28.