Pietersen has been left out of the England squad for the match at Lord's after reportedly refusing to publicly acknowledge that he had sent texts about Andrew Strauss and Andy Flower to members of the South African team.
However, Kirsten claims that the Proteas won't be distracted by the saga and that the team are fully prepared for the final Test in the series.
"We will focus on our preparation and the work that we do," Kirsten said. "We respect our opposition, we understand that we are playing against quality opposition, we'll never take any Test match for granted.
"We don't really focus heavily on individuals, we look at their team make-up and we won't do anything different to a normal Test match."
South Africa's team manager has played down the texts from Pietersen in a press conference held on Monday.