Shares in Barclays closed over 5 percent lower after the British bank published its interim management statement. It reported a 5 percent fall in first-quarter adjusted pre-tax profit to £1.7 billion ($2.9 billion), as the fixed-income division of its investment bank slowed dramatically.
Investment manager Aberdeen Asset Management closed around 2.6 percent lower, after results showed clients pulled money out of its core emerging market and Asian equity funds.
Fierce clashes reportedly broke out in the eastern Ukraine region of Slavyansk on Monday. Four Ukrainian soldiers are believed to have been killed, and an army helicopter shot down by pro-Russian militants.
Pro-Russian militants seized government buildings in a dozen or more Ukrainian cities in the east. Kiev accuses Moscow of supporting and arming the gunmen—a claim Russia denies.
Merger and acquisitions remained in focus in Europe on Tuesday.
German drug maker Bayer announced its plans to acquire the consumer care business of U.S.-based Merck & Co for $14.2 billion in cash. Shares in Bayer closed down around 0.9 percent after the news.
The deal is the latest in a flurry of activity in the pharmaceutical space, which has seen a record volume of mergers and acquisitions this year, according to data provider Dealogic.
Meanwhile, data out on Tuesday showed business activity in the euro zone hit a three-year high in April. New orders and backlogs of work saw Markit's final euro zone purchasing managers' composite index come in at 54.0, up from 53.1 in March.