European stock markets moved lower on Monday, with AstraZeneca PLC leading the charge south after rejecting a sweetened Pfizer offer, while mining firms declined on added signs of a slowdown in the Chinese housing market.

The Stoxx Europe 600 index gave up 0.7% to 336.77, after closing higher for a fifth straight week on Friday.

Posting the biggest loss in the benchmark, shares of AstraZeneca (AZN) tumbled 13% after the U.K. drug maker rejected a "final" offer from Pfizer Inc. (PFE) at 55 pounds a share ($92.48). Leif Johansson, chairman of AstraZeneca, said the offer is only a minor improvement over the previous bids and continued "to fall short."

Mining firms were also adding pressure in Europe, falling on signs that the Chinese real-estate market continues to cool. Beijing's prices for second-home purchases dropped in April by the most in two years, while newly-built residential-housing price gains eased for the sixth straight month, according to data from China's National Bureau of Statistics.

Shares of Rio Tinto PLC (RIO) dropped 1.8%, BHP Billiton PLC (BHP) gave up 1.3%, and Anglo American PLC slipped 1%.

The AstraZeneca slide and the losses for miners weighed on the FTSE 100 index . The U.K.'s benchmark erased 0.5% to 6,819.32.

More broadly, Europe's stock markets were also weak as investors watched the latest flare-up in tensions between Ukraine and Russia, with clashes in Ukraine's east continuing over the weekend.

"With the Ukrainian presidential election scheduled for May 25, markets are worrying the tensions will rise ahead of the elections as rebels who want to vote in eastern parts of Ukraine say they want to join Russia," market strategists at ETX Capital said in a note.

Germany's DAX 30 index fell 0.4% to 9,588.27, while France's CAC 40 index slipped 0.4% to 4,437.07.

Italy's FTSE MIB index tanked 2.5% to 20,134.45, as more than 20 companies in the benchmark traded without the right to their latest dividends, according to Bloomberg.

Shares of Banca Monte dei Paschi di Siena SpA slid 4.5%, Banco Popolare SC lost 3.2%, and Telecom Italia SpA dropped 2.6%.

Shares of Deutsche Bank AG (DB) shaved off 2.1% in Frankfurt after the bank said on Sunday it plans to raise 8 billion euros ($10.97 billion), with EUR1.75 billion coming from Qatar's Paramount Holdings Services Ltd.

Belgacom SA erased 0.9% in Brussels after Berenberg cut the telecom firm to hold from buy.

On a more upbeat note, shares of Ryanair Holdings PLC rallied 7.4% after the budget airliner said profit should grow this fiscal year, after reporting a drop in full-year profit for the year ending March 31.

Outside the main indexes, shares of Vestas Wind Systems AS rose 1.1% after the Danish wind-turbine maker received a 148 MW order in the U.S.