Ahead of a visit by Greek leaders to Berlin this week, senior politicians are making it clear the German government does not welcome the idea of a blank check.
Greek Prime Minister Antonis Samaras is expected to ask for a two-year extension to the deadline international lenders have set when he meets the leaders of Germany and France this week.
Greece is in its fifth year of recession and has fallen behind on its targets. It will probably need to make 14 billion euros ($17.24 billion) in cuts rather than a previously expected 11.5 billion euros over the next two years to meet terms for international aid, according to Germany's Der Spiegel magazine.
Norbert Barthle and Michael Meister, both senior politicians in Chancellor Angela Merkel's Christian Democrat party (CDU), told German daily newspaper Tagesspiegel there would be no third aid package for Greece.
Finance Minister Wolfgang Schaeuble said on Saturday at a government open day in Berlin: "It is not responsible to throw money into a bottomless pit."
Volker Kauder, head of the conservatives in parliament, said: "There is no room for maneuver there, neither in terms of the time frame nor in terms of the substance because that would be another breach of the agreements."
Kauder added that he saw little chance of a third aid package for Greece finding support in the coalition: "Greeks must at some point answer the question: Are we going to make an effort or are we going to leave the euro?"
Junior coalition partners, the Free Democrats (FDP), confirmed the point. General Secretary Patrick Doering said in an interview to be published Monday that the basis for aid was "the second aid package and the conditions to which Greece has committed itself. That is not negotiable."
Foreign Minister Guido Westerwelle told a Sunday newspaper that Germany would not consider easing agreed reforms "in their substance” and called on the Greek government to "take the German government's position very seriously."
Inspectors from the International Monetary Fund, the European Commission and the European Central Bank - known as the troika - are due back in Greece in September. The Greek government is trying to negotiate an additional two years in which to cut its budget deficit.
jm/xxx (Reuters, dpa)