Reus, who has already struggled with injuries this season, was forced off with an ankle issue following a strong challenge from Marvin Bakalorz during Saturday's 2-2 draw at Paderborn, having netted his side's second goal before the hosts battled from 2-0 down to earn a share of the spoils.
The incident clearly infuriated Klopp, who told the club's official website: "I find it hard with the injury of Marco Reus to talk about football.
"I have no problem with the draw, and I have great respect for the work that is being done here in Paderborn."
But Klopp refused to blame the result on the injury to Reus, conceding his side's performance in the second half was simply not good enough.
He added: "In the first half we had many things right - in the second less.
"Thus, a different game originated, and we allowed them to cause problems with the long balls."
Klopp is adamant that his side would have sealed the win were it not for Kevin Grosskreutz's effort being controversially ruled out for offside when Dortmund were 2-1 in front.
He added: "Anyone who has seen the alleged offside goal, will probably join my opinion, that it [the goal] should not have been waved away.
"This was again not a good day for us. We have to work. Quality is what you make of the existing potential. We were good in some moments, in some others a bit less, and so we left them [Paderborn] alive."
The result means Dortmund are 15th in the Bundesliga.
