The parliament has approved pension cuts and tax hikes
Protests have been sparked in Greece after the government recently approved new austerity measures in order to access financial aid.
Protesters converged in central Athens to stop the measures as the parliament approved pension cuts and tax hikes.
The austerity measures were forecasted earlier this month, after a preliminary deal was reached after six months of negotiations.
The move - which was approved by the country's leftist government Syriza - is an attempt to convince lenders to release a €7.5bn bailout package and grant it further debt relief.
Without these funds, Greece would more than likely struggle to meet its debt servicing obligations in July.
Shortly before the measures were approved at around midnight Thursday, protesters gathered outside parliament buildings chanting "No more tax theft."
They later clashed with police as some protestors hurled petrol bombs and firecrackers at police, who in turn released tear gas.
Speaking about the austerity measures, Prime Minister Alexis Tsipras said: "We deserve and we expect from Monday's Eurogroup a decision regulating debt relief which will correspond to the sacrifices of the Greek people."
Mr Tsipras was referring to an upcoming meeting of Eurozone finance ministers next week.
Although the country's lenders have agreed in principle to debt restructuring, they have not necessarily agreed on the details.
Greece's national output has shrunk by a quarter since it was first forced to seek external financial aid in return for spending cutbacks in 2010.