In its latest Financial Stability report, the German central bank also called for more transparency for hedge funds, and said the risk of sudden liquidity shortfalls was serious for this sector.
But overall, the German banking sector was in a much better position than in 2001 and 2002, when corporate collapses forced banks to write off bad loans.
"The robustness of the German financial sector is more than satisfactory, and stability has improved in the course of the year," Bundesbank President Axel Weber said at a press conference to launch the report.
Improved bank profitability, robust global growth against a backdrop of low inflation, and favourable financing conditions on world markets had helped strengthen the system.
But at the same time, there were risks, especially from ongoing high oil prices, potentially weaker consumption in the United States, and reduced prospects for a smooth unwinding of global imbalances.
Bundesbank Vice-President Juergen Stark said the international environment was particularly important for Germany, where growth has been largely driven by exports.
"None of these risk factors pose an acute danger to the financial system," he said.
"But for all that, they could lead to a noticeable slowing in global growth ... it is certainly feasible that two or all three of these negative effects might happen at once."
High oil prices dampened growth and US interest rate rises could crimp private consumption, given high private debt, and rob the economy of its major driver.
The Bundesbank said excess liquidity world-wide as well as in the euro zone was another risk to financial stability, but the opposite could also occur.
"Sudden liquidity shortages in individual markets with perhaps sharp price surges are a risk that has to be taken seriously," the report said, pointing to hedge funds' increasing preference for investing in non-liquid assets.
Banks had to be careful about risk management when lending to such funds.
"Increasing the transparency of hedge funds should be a high-priority goal," the Bundesbank said.