Die Schwarzgelben claimed all three points thanks to Pierre-Emerick Aubameyang's first-half strike but were sluggish in their play and Burki was called into action on a number of occasions.
Despite winning six of their last seven games in all competitions, Thomas Tuchel’s men have struggled to produce their best form.
The goalkeeper was less than impressed with their performance on Friday, insisting that for all of their endeavour, they must start to limit the chances they give the opposition if they are to improve.
He told the club's official website: "Absolutely. We gave it absolutely everything until the end. I'm very happy that Auba got that goal because otherwise it would've got a lot tougher. Especially towards the end we could've definitely been a bit more comfortable.
"We weren't clever enough and gave chances away we shouldn't have. Getting the three points was the most important thing."