The STOXX 600 <.STOXX> index closed 0.2 percent lower at 387.09, adding to the previous session's losses, while Britain's FTSE <.FTSE> was down 0.3 percent and France's CAC 40 <.FCHI> was flat.
The pan-European index ended the week up 2.5 percent - its strongest week since December - as fresh money poured into the region's equities on the back of the market-friendly outcome of the first round of France's presidential election.
It sealed a third straight month of gains, and was just off fresh 20-month highs hit on Wednesday.
Brokers and investors fell over each other to recommend European equities. Strategists at Bank of America Merrill Lynch raised their target for the STOXX to 420 points and said they expected European earnings to grow 15 percent this year.
"If valuations look as high as they can reasonably get, the market has to be driven by earnings growth to go higher from here. And we are confident we will see that," said Andrew King, head of European equities at BNP Paribas Investment Partners.
"That's why this reporting season could be significant - it might go a long way to convincing overseas investors that Europe is not broken, and that a recovery is underway," he added.
Of the 28 percent of companies having reported, 71 percent have beaten estimates while 20 percent missed, Thomson Reuters data showed.
The biggest inflow into European equity funds since 2015 helped bolster market optimism over the region.
On the day, shares in UBS (>> UBS Group AG) rallied 2.2 percent, touching a three-month high as a long-awaited turnaround in its core wealth management business helped Switzerland's biggest bank deliver its second-best start to a year since the financial crisis.
Baader Helvea analyst Tomasz Grzelak said the recovery in wealth management "will significantly lower investor concerns" about the bank's key growth engine.
But British rival Barclays (>> Barclays PLC) fell 5.1 percent after its investment bank missed out on a bond trading boom that saw earnings surge at its Wall Street rivals, even though its first quarter profit more than doubled.
Austrian oil and gas company OMV (>> OMV AG) jumped 8 percent to a 9-year high after its first-quarter profit nearly tripled thanks to higher oil prices and better sales.
Gemalto (>> Gemalto) fell 7.2 percent, the biggest faller on the STOXX after the Dutch digital security firm cut its 2017 profit forecast due to slow adoption of chip-enabled payment cards in the United States.
Earnings also drove price action for other top STOXX movers.
French tele-services provider Teleperformance (>> Téléperformance) surged more than 7 percent to an all-time high following better than expected results, while aluminium producer Norsk Hydro (>> Norsk Hydro ASA) fell 5 percent after posting first-quarter results below forecasts across all divisions.
Deal news was the driver of Zodiac (>> Zodiac Aerospace) shares, which climbed 6.9 percent after the struggling airplane seat-maker said it was continuing talks with Safran (>> SAFRAN) to seal a merger.
(Reporting by Danilo Masoni; Editing by Mark Trevelyan)
By Danilo Masoni and Helen Reid