Marco Reus and Robert Lewandowski both scored twice before Jakub Blaszczykowski rounded off the scoring as Dortmund dominated their beleaguered opponents, who had defender Fallou Diagne sent off on the stroke of half-time for a professional foul on Lewandowski that led to Reus' second goal from the penalty spot.
The win leaves Dortmund top of the Bundesliga on goal difference with six wins and a draw from their first seven matches and after the game, Klopp waxed lyrical about the way his side had played.
"We were on the front foot for the entire second half," he said. "When my team play like that, of course, it makes the job fun.
"But I also found the first half really good. I was really pleased with our counter pressing there.
"After the red card and the penalty, Freiburg then had nothing to oppose us with."
Klopp described Lewandowski's first goal as "outstanding", before looking ahead to Tuesday's UEFA Champions League tie with Marseille.
"Tuesday will be a challenge," he said.
"But we have a home game before a packed house. We do not feel terribly under pressure, we have analysed the game against Napoli (a 2-1 defeat in their last Champions League game) in detail."
Reus' brace means that the midfielder has now scored twice or more in a Bundesliga game on 11 occasions, and the Germany international was pleased with the way his side had kept pushing for more goals.
"The game today has also shown that we always want more," he said.
"A 2-0 or 3-0 is not enough for us. We always want to go and get another one."
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