In fierce street battles that began in the early hours today in the well-heeled western city, 14 German police and 21 anti-capitalist protesters were injured, police and rally organisers said.
Police also said they had made 16 arrests by 1330 GMT, mostly on charges of disturbing the peace and arson after seven police cars were set ablaze.
They added that 80 of their officers had been hurt by an irritant gas, but were back on duty, while Blockupy protest organisers said on Twitter that 107 demonstrators were hurt by tear gas and pepper spray.
"I would have hoped that the morning protests would be very different," the organisation's spokesman Ulrich Wilken told a news conference. "This is not what we in Blockupy had planned."
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At the same time, Wilken said he "understood" people's anger at the "policies of impoverishment" being imposed by governments on people in the crisis-hit countries.
However attacks on fire brigade vehicles have no place in demonstrations in Germany, Wilken insisted.
Another Blockupy spokesman, Christoph Kleine, estimated that around 6,000 activists had taken part in the morning's activities, including 1,000 from outside Germany.
Kleine argued that police should shoulder some of the blame for the morning's violence, accusing them of using excessive force to provoke demonstrators.
In Berlin, leading politicians condemned the chaotic scenes.
Finance Minister Wolfgang Schaeuble said that "no-one has the right to threaten life and limb of police and firefighters".
Economy Minister and Vice Chancellor Sigmar Gabriel said that to blame the ECB for Europe's woes "testifies to a significant lack of understanding about what the ECB is currently doing for cohesion in Europe".
Addressing some 100 invited guests at a low-key ceremony, Draghi rejected blame for the suffering brought by budget cuts and austerity policies amid the financial crisis in Europe.
"As an EU institution that has played a central role throughout the crisis, the ECB has become a focal point for those frustrated with this situation," Draghi said.