The midfielder was recently sidelined for a month after suffering an ankle problem during Germany's win over Scotland in Euro 2016 qualifying.
Despite the 25-year-old being out of action for the next four weeks, Klopp is not overly worried by the effect that Reus's absence will have on his side.
"It could have been worse," he told Bild. "I am, of course, very sorry for Marco but four weeks will go quickly. We just have to work now and score without him."
Dortmund continue their Bundesliga campaign on Saturday when they host Freiburg.