The European Trade Union Confederation (ETUC) said about 350,000 people had taken part in marches in Madrid, Brussels, Berlin and Prague to demand more government action to save jobs.
It blamed a lack of transparency in banks and their short-term quest for profit for the crisis, which has forced taxpayers to bail out financial institutions.
ETUC General-Secretary John Monks said such "greed and selfishness" should never again be allowed to cause trillions of euros of damage. "Tighter regulation of financial markets is needed now and more workers influence on boardrooms. Workers want life support systems for industry and jobs too," he added in his statement.
The economy of the 16 countries sharing the euro shrank by 2.5 percent in the first three months of 2009, much more than expected, data showed on Friday.
The European Commission and EU governments says the agreed fiscal stimulus package amounting to five percent of the bloc's economic output is sufficient for now to battle the worst recession since the World War Two.
The Commission will present on 27 May its ideas for reforming financial regulation, which will be then debated by the EU's 27 governments.
(EurActiv with Reuters)
