Other economists were puzzled by the data, remarking that it showed German investors were "a bit confused."
"The positive trends of the first months of the year have been (partly) reversed over the last four weeks," Carsten Brzeski, chief economist at ING Germany, said in a note Tuesday, highlighting that the euro had strengthened, oil prices had increased and government bond yields had more than quadrupled.
But he added that there were very few arguments in favour of taking a more negative approach towards to country.
"In fact, even if the external tailwinds have subsided somewhat, they are still there," Brzeski said. "Just to put latest developments into perspective: compared with their average value of the last 12 months, bond yields are currently still some 20bp (basis points) lower, the euro some 10 percent weaker and oil prices almost 30 percent cheaper. Still sufficient to give the economy a cool breezy boost."
McKeown agreed that Germany's outlook still looked relatively positive. Capital Economics forecast German gross domestic product (GDP) to rise by up to 2 percent this year, although "a renewed appreciation of the euro or further intensification of the Greek crisis would imply slower growth."