Restructuring the national debt would, Papandreou said, be catastrophic for Greece's economy, its credibility and its future - and it would likely cause the collapse of the Greek banking system.
During a keynote speech, he outlined plans to reform the hospital sector, the energy market and the railway.
The country's train service is some 6 billion euros in debt with annual expenditure of 700 million euros, seven times its income.
Papandreou also confirmed plans to liberalise the road haulage industry, a policy that led to a week-long strike by truckers in July.
Road haulage unions yesterday announced another open-ended strike from tomorrow.
There have been six general strikes this year and unions have promised more industrial unrest in the coming months.
The International Monetary Fund said on Friday it would provide Greece with a further 2.57 billion euros in its second instalment of the rescue package, after Athens met tough demands to cut public spending.
Papandreou promised to set aside 3.5 billion euros to ensure that the jobless and other vulnerable groups would be protected.