Rocks and Molotov cocktails have been hurled at the Greek parliament while politicians inside approved the latest package of austerity measures.
Left-wing Prime Minister Alexis Tsipras was elected on a mandate of rejecting austerity, but has been forced to adopt the measures to unlock Greece's next instalment of multi-billion dollar bailouts.
However, despite approving the pension cuts and tax hikes, the fate of his country is now in the hands of Euro zone finance ministers who will decide on Monday (22 May) whether to release the funds.
"It's their [the lenders'] turn to fulfil their commitments, just like we did," Tsipras said after the meeting, reported the BBC.
"We deserve and we expect from Monday's Eurogroup a decision regulating debt relief which will correspond to the sacrifices of the Greek people."
If the funds are approved, they will receive a €7.5bn (£6.4bn; $8.3bn) loan plus debt relief, which will go towards financing its next debt obligations in July.
Tsipras said the move was necessary to stop Greece from sliding into further crisis, but the move was not popular with protesters.
Over 10,000 people gathered outside the Parliament building in Athens, in mostly peaceful protests at the austerity politics, but several broke away to throw the petrol bombs at the building.
Police fired tear gas in return, but in a statement, confirmed there were no arrests and no injuries.
The new austerity policies also drew criticism from Tsipras's main opposition in parliament.
"You've become the best advertisement for austerity in Europe," opposition Conservative leader Kyriakos Mitsotakis told Reuters.