In Europe, the Stoxx 600 Index slid 0.5 per cent from the previous close. The UK's FTSE 100 Index fell 0.3 per cent, France's CAC 40 shed 0.7 per cent, and Germany's DAX dropped 1.1 per cent.
"I can't see any panic selling. It is only just that people are not willing to buy," Soeren Steinert, associate director for equities trading at Quoniam Asset Management in Frankfurt, told Bloomberg News. "There is no conviction that the market should be falling further."
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In a monthly report, the Bundesbank said Germany's economy endured a tough second quarter.
"Industry shifted down a gear. As well as calendar effects, increased geopolitical tensions likely played a role in this," it said.
While the German central bank was cautious, the International Monetary Fund said it's still expecting the EU's powerhouse to expand 1.7 per cent in 2015, up from an earlier 1.6 per cent forecast.
US Treasuries advanced, as did German bunds, as some investors sought refuge from the uncertainty in the safety of fixed-income securities. Yields on the benchmark 10-year bond fell one basis point to 2.47 per cent.
Gold also received a bid for the same reason. Spot gold gained 0.2 per cent to US1,312.50.
"It's Gaza, Israel, Iraq, Ukraine ... everything that has a sort of potential flashpoints that could resurface to be keeping gold above the US$1,300 mark," Societe Generale analyst Robin Bhar told Reuters.
So far the latest quarterly US earnings season has been solid. About 76 per cent of S&P 500 companies that have posted results this season have beaten analysts' estimates for profit, while 69 per cent exceeded sales projections, according to data compiled by Bloomberg.
Companies scheduled to report this week include Apple, Facebook, Microsoft as well as Boeing and Caterpillar.