He also welcomed the official launch Monday of Europe's new $647.9 billion permanent bailout fund, the European Stability Mechanism (ESM).
"We have enough challenges in Europe," Rehn said as he entered a meeting of finance ministers from the eurozone. He added that while nobody was in a "party mood," he was "less pessimistic for the moment of the future prospects of the eurozone than, for instance, in the spring."
In recent months, the EU has acquired significant new powers designed to help it resolve the current crisis and prevent new ones. These include the power to closely monitor national budgets and, where needed, demand changes in them. Also in the works is a central banking supervisor.
The new ESM is designed to reassure investors that the EU is better equipped to contain whatever crises erupt in the eurozone.
"Today is a good day for Europe," said Jean-Claude Juncker, the prime minister of Luxembourg, who is also chairman of the ESM's board of governors.
The new fund will eventually have 500 billion euros at its disposal that it will use to buy up the bonds of countries whose borrowing costs are becoming unmanageable and, if that's not enough, to also lend money to them. It will also lend money to countries that need to prop up failing banks, including handling Spain's bank bailout. It is expected that the fund will eventually be able to lend money directly to banks.
The ESM will eventually replace a temporary bailout fund, known as the EFSF, but the two will overlap for the time being while the EFSF continues to handle the bailouts of Greece, Ireland, and Portugal.
The eurozone finance ministers, meeting in Luxembourg, were expected Monday to assess developments rather than make major new decisions. The countries considered in the most tenuous financial condition now are Greece and Spain. International lenders are still preparing a report on Greece, and no new disbursement of bailout money will be approved until that report.
And while some have speculated that Spain may need to request help in keeping the cost of its borrowing down, Spanish officials have made no request. In the absence of that, EU officials cannot act.