Greece's public transport, health, and other services have come to a halt at the start of a 48-hour general strike.
Labor unions called the strike in response to the government's austerity plan.
In downtown Athens, some 16,000 people staged a protest that ended peacefully.
During a march in Athens to protest the austerity measures, one taxi driver told Reuters: "I don't know if we will have the power to stop the bill from passing. What we can do is fight, we are not just professionals but also citizens and we are being attacked both as Greeks and as workers."
"It's difficult to find work. To find work with decent conditions is impossible. To work for 12 hours with half the salary, half the wage, and with the risk of being fired hanging over your head, this is not work, it's forced labor," another marcher said.
"To live with 400 euros with the needs that a family has -- and not just a family, a single person cannot live with this money. Who and where can you go on living like this?"
Kostas Tsikrikas, leader of the Civil Servants Confederation (ADEDY), described the government's austerity plan as "unfair" and "painful."
"They are measures that will create chaotic labor conditions and ruin the country financially," he added.
Greek Finance Minister Yannis Stournaras, meanwhile, urged parliament to approve the austerity plan "to avoid a hard bankruptcy."
The parliament is due to vote on November 7 on the plan.
It provides for 13.5 billion euros ($17 billion) in budget cuts and tax hikes.
Approval of the reforms and the passage of the 2013 budget are crucial to unlocking 31.5 billion euros ($40 billion) in aid from an International Monetary Fund and European Union bailout that has been on hold since May.
Alexis Tsipras, leader of Greece's main opposition Coalition of the Radical Left, said the opposition would continue to resist government plans.
"We will not allow them to give our country away, we will force them to succumb to the public will very soon," Tsipras said.
"We will take back the country, our dignity, and the dreams of the youth."
Labor unions called the strike in response to the government's austerity plan.
In downtown Athens, some 16,000 people staged a protest that ended peacefully.
During a march in Athens to protest the austerity measures, one taxi driver told Reuters: "I don't know if we will have the power to stop the bill from passing. What we can do is fight, we are not just professionals but also citizens and we are being attacked both as Greeks and as workers."
"It's difficult to find work. To find work with decent conditions is impossible. To work for 12 hours with half the salary, half the wage, and with the risk of being fired hanging over your head, this is not work, it's forced labor," another marcher said.
"To live with 400 euros with the needs that a family has -- and not just a family, a single person cannot live with this money. Who and where can you go on living like this?"
Kostas Tsikrikas, leader of the Civil Servants Confederation (ADEDY), described the government's austerity plan as "unfair" and "painful."
"They are measures that will create chaotic labor conditions and ruin the country financially," he added.
Greek Finance Minister Yannis Stournaras, meanwhile, urged parliament to approve the austerity plan "to avoid a hard bankruptcy."
The parliament is due to vote on November 7 on the plan.
It provides for 13.5 billion euros ($17 billion) in budget cuts and tax hikes.
Approval of the reforms and the passage of the 2013 budget are crucial to unlocking 31.5 billion euros ($40 billion) in aid from an International Monetary Fund and European Union bailout that has been on hold since May.
Alexis Tsipras, leader of Greece's main opposition Coalition of the Radical Left, said the opposition would continue to resist government plans.
"We will not allow them to give our country away, we will force them to succumb to the public will very soon," Tsipras said.
"We will take back the country, our dignity, and the dreams of the youth."