The pan-European STOXX 600 fell 1.0pc, retreating from its strongest close in three weeks, led by declines in travel and leisure, banks and technology stocks.
Data released earlier showed the pandemic's devastating effect on the euro zone economy abated a little in May as lockdowns imposed to contain the spread of the virus were eased, but was still a long way from marking a growth.
After having crashed to rock bottom in April, the IHS Markit's Flash Composite Purchasing Managers' Index recovered to 30.5 from April's 13.6.
Stock markets globally have made headway this week as optimism over easing lockdowns and talks of more stimulus for the battered euro zone revived hopes of a recovery.
However, rising US-China tensions and concerns about the longer-term outlook have stalled a strong rebound in markets from mid-March lows.
"We are starting to see a bit of lag in momentum," said Craig Erlam, senior market analyst at Oanda. "Until we see the countries reopen and fully understand what the negative implications are going to be, there's only so far the rally can continue."
The US Senate on Wednesday passed legislation that could prevent some Chinese companies from listing their shares on US exchanges, adding to woes after intense criticism by the Trump administration on Beijing's handling over the coronavirus crisis.
Among individual movers, Amsterdam-based telecoms and cable group Altice Europe NV slumped 14.3pc as it posted a worse-than-expected first-quarter core profit.
Premier Inn owner Whitbread Plc tumbled 12pc after revealing plans to raise 1.01 billion pounds ($1.23 billion) through a rights issue as the company looks to bolster its balance sheet amid the pandemic.
Lufthansa rose 4.6pc amid talks with the German government over a rescue deal worth up to 9 billion euros ($9.9 billion), including the state taking a 20pc stake.
British low-cost airline easyJet gained 3.3pc after saying it would restart a small number of flights on June 15.
Markets in Sweden, Denmark and Norway are closed for a public holiday.