Klopp led his side into the Champions League final during a successful 2012-13 campaign, but injuries and a drop in form has left the German side trailing already-champions Bayern Munich by 23 points in the Bundesliga this season.
However, the German is confident that his team can enjoy a successful end to the campaign.
"That's not the way I see it. It's been a very difficult season from the beginning. We have faced extraordinary challenges and an unprecedented injury crisis. I've never seen anything like it," he told Marca.
"But in spite of everything, we are on the road to achieving all the goals we set ourselves at the start of the season. So you can't talk about us playing worse or not being as strong as we were.
"We're second in the Bundesliga, we're in the Cup semi-final and we have made it to the quarter-finals of the Champions League, just like last year."
"And don't forget, we came top in the toughest Champions League group just like we did last season... we never give up."
Dortmund face Real Madrid in the first leg of their Champions League quarter-final clash on Wednesday.