The European Commission has welcomed the Greek parliament’s decision to approve tough new austerity measures.
Economics commissioner Olli Rehn urged Greek officials to “take ownership” and fully implement the reforms, demanded by the EU in return for a huge bailout.
Financial markets were up slightly after the austerity bill was passed.
But the measures attracted massive protests throughout Greece. Buildings were set on fire in Athens and police used tear gas to disperse the crowds.
Greece is trying to secure a 130bn euro ($170bn; £110bn) bailout from the EU and IMF to allow it to repay its debts.
But the lenders have insisted that Athens implements deep cuts and austerity measures before the money is released.
It is the second major programme of cuts the Greek government has promised to carry out.
Mr Rehn said the EU continued to stand by the Greek people, and insisted that the cuts were needed to ensure future economic growth.
“The Greek authorities and political forces should now take full ownership and make the case for the second programme and fully implement it in order to return the country to stable economic growth and job creation,” he said.
The EU has been the target of much anger among Greeks, who see the reforms as piling unnecessary hardship on ordinary people.
Tens of thousands protested against the measures in Athens on Sunday night.
Although most of the demonstrators protested peacefully, small groups were involved in running battles with riot police.
They did huge damage to the city, attacking buildings with petrol bombs, setting fire to banks, cinemas and cafes.
In all, 45 buildings are said to have burnt in the worst rioting for years