The fierce rivals will go head to head for the first time in a European competition this week when Liverpool host Louis van Gaal's side on Merseyside.
Klopp believes that the supporters can play a part, and has challenged the crowd to create an atmosphere that United fans will not be able to rival on their turf next week.
"Everybody needs to be in the best shape and the crowd is involved," Klopp told reporters in Wednesday's press conference. "I believe in the influence of the crowd.
"We do it for ourselves but we also do it for them. We can show we can create a better atmosphere in the first leg than Man United in the second leg. It's a big part of football. Hopefully tomorrow we set an absolutely new level."
United have beaten Liverpool in their last four meetings.