Tear gas and stun grenades were used to quell the violence amid wide-spread anxiety over the impact of the plan, which is linked to a needed bailout for the Greek economy, CNN said.
The Greek prime minister gave a final warning Sunday that the nation faces economic disaster if parliament rejects a strict austerity plan.
Parliament was to vote later in the day on the controversial measure, which is tied to a major bailout of the faltering Greek economy by the European Union and the International Monetary Fund.
The plan includes government job cuts, pension reductions and a 22-percent cut in the minimum wage; however Prime Minister Lucas Papademos said in a televised address the alternative would be Greece being "drawn into a vortex of recession" and its eventual departure from the euro, Euronews.net said.
Despite the dire warnings, Ekathimerini, reported Sunday a number of opposition members said they would vote against the proposal. The ruling coalition government, however, seemed to have the votes needed to carry the day.