In the first minutes of trade, the Dow Jones Industrial Average was down 15.06 points (0.13 percent) at 12,030.62.
The broader S&P 500 lost 2.56 (0.21 percent) to 1,244.40, while the Nasdaq Composite eased by 5.40 points (0.21 percent) to 2,614.94.
"Wall Street is keeping one cautious eye across the pond, where conflicting news from all corners has traders a bit on edge," said Karee Venema of Schaeffer's Investment Research.
"Specifically, France and Spain enjoyed bond rallies, in spite of European Central Bank President Mario Draghi's words of caution on the economy. China also remains on the scene, as on the heels of a positive central bank move, the country experienced a contraction in its manufacturing sector," she said.