Any purchase of bonds by the European Central Bank must be linked to clear commitments to structural reform and budget discipline, German Economy Minister Philipp Roesler has said.
Mr Roesler is head of the Free Democrats (FDP) who share power with Chancellor Angela Merkel's conservatives.
He also said the euro must not be allowed to fail due to a lack of effort by countries at the frontline of the euro zone debt crisis to overhaul their economies.
"(ECB President Mario) Draghi has himself emphasised that bond purchases can never replace structural reforms and budget discipline. We take him at his word. That is the right road to follow," Mr Roesler, whose FDP has been more sceptical about bailouts than Merkel's Christian Democrats (CDU), said in an interview.
Mr Draghi signalled earlier this month that the ECB may start buying government debt to reduce crippling Spanish and Italian borrowing costs but he also said any intervention would only come if governments requested euro zone aid first. That in turn would be linked to conditions.
Many Germans, including Bundesbank chief Jens Weidmann, have major reservations about a new bond-buying programme, fearing it would reduce the pressure on governments to cut debt and make their economies more competitive.
Mr Roesler, who has previously said the notion of Greece leaving the euro zone has "lost its horror", said the failure of individual member states to implement structural reforms could not be allowed to bring the single currency to its knees.
"We have all agreed in the Fiscal Pact about the importance of budget discipline and reforms," he said. "There are no benefits without a trade-off."
"We are all convinced: we need a strong Europe with a strong currency but this currency must not be allowed to fail due to a lack of reforms in individual member states."
Greece is a major source of worry for Berlin. Athens is falling short of the budget cut and privatisation promises it made in March to obtain a second, 130-billion euro bailout from the European Union and the International Monetary Fund.
This has led to calls by several German politicians for Greece to be ousted from the euro zone as many doubt Athens is serious about implementing the tough measures needed to cut its deficit.
Greek Prime Minister Antonis Samaras meets Merkel next week and may seek more time to implement his austerity plans.
There are growing signs that the debt crisis is starting to take a toll on a German economy which had been growing robustly.
Data released on Tuesday showed growth in Europe's biggest economy slowed in the second quarter, triggering worries about a sharp slowdown, even recession.
Mr Roesler said he would not join the debate about recession.
"I am not using the term," said Mr Roesler. "We have a robust economy. On the other hand, we are seeing uncertainty within the euro zone which is having an effect on our companies. The forecast remains 0.7% growth (for 2012) which we made earlier this year."
Mr Roesler's economy ministry will decide whether to revise its forecasts in the autumn. It estimates 1.6 growth for next year.
"Our main job is to stabilise the euro zone ... At the same time we have to do what we can to improve competitiveness of the German economy," he said.
To that end, his party - whose popularity has dived to around 5% in polls from over 14% at the last election - is campaigning for lower pension contributions, affordable energy and to ensure Germany has enough qualified workers.
