The striker netted the opener in the 4-1 thrashing of England on Sunday but expects a much tougher test in the last eight in Cape Town on Saturday.
"We shouldn't compare Argentina with England. Argentina are in another league," Klose, at 32 the elder statesman in a young Germany team, told a news conference.
"The key factor is presenting yourself as a team, as a unit, and I didn't really think this was the case with England. We realised six or seven minutes in that maybe they were not really up for it and we could beat them."
"I think a lot has changed with Argentina, the same is true with Germany. In 2006 Messi was sitting on the bench," added Klose, who has scored 50 goals for his country and will pick up his 100th cap against Diego Maradona's men.
"If you look at the names on a case-by-case basis, Argentina should been seen as stronger on paper. It was the same with England, on paper they were more renowned and famous, but it didn't happen on the pitch. Germany are a 'tournament team'."
"It is always an enriching experience to get away from it, to unwind. We deserve to be given free rein for a few hours and then we can concentrate on Argentina," said midfielder Sami Khedira.
"There's no way you can contain this guy for 90 minutes. It will have to be a collective effort to keep him at bay. Other than Messi they have other great players but there's no reason to hide. We do have a chance against Argentina," he said.
