The Commission said its key confidence index in March fell 1.1 points from February to 90 points, reflecting a downturn in the manufacturing and service sectors while consumer sentiment was steady overall.
For manufacturing alone, the confidence index shed 1.2 points in March while services, the major part of the economy and which had been on the rise since October, lost 1.4 points on concerns over future orders.
Consumer confidence edged up 0.1 point, reflecting a slightly more positive view on employment prospects.
France was the worst performer in March, with the main index reading falling 1.7 points while Germany, the biggest European economy, was down 1.6 points and Spain off 0.9 points.
Italy showed an increase of 1.4 points.
For the 27-member European Union, the index shed 0.6 points to 91.4.
Howard Archer of IHS Global Insight said the figures suggest the eurozone economy will have shrank again in the first quarter, adding to concerns over the outlook.
"The slippage in business sentiment in March is not good news for investment and employment prospects," Archer said in a note.
"Confidence is still low compared to long-term norms while eurozone consumers still largely face high and rising unemployment, generally muted wage growth and tight fiscal policy," he said.
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