Schäuble said after a meeting in Berlin with senior representatives from German banks and insurers, that the agreement covered some €3.2 billion ($4.6 billion) in investments in Greek bonds due to expire before 2014.
The exact details, however, remain to be hammered out.
"I am confident that we will have a solution by (a meeting of eurozone finance ministers in Luxembourg) Sunday and then we'll work further on the follow-up to the decisions over the coming weeks," Schäuble said.
"I'm happy that the representatives of the financial sector have said they are ready to participate in a European package for a second aid programme for Greece," he told reporters.
Josef Ackermann, chief executive of Deutsche Bank, said: "We are of the opinion that Greece must be helped ... We are ready to do so."
Ackermann said that the banks, which together hold around €20 billion in Greek assets, chose to follow the outline of a proposed deal with French banks announced by President Nicolas Sarkozy earlier this week.
That arrangement involved French banks agreeing for maturities on some Greek government bonds to be extended by 30 years.
"But we must still add some modifications," Ackermann cautioned.