"We are playing with fire," Sergio Marchionne, who is also Fiat SpA's chief executive officer, said at Detroit's North American International Auto Show.
"One of the things we need to realize is that the world is fundamentally interconnected. We have ended up being accountable to a lot of people who financed our public debt," he said.
"Europe is being called to task to solve a number of issues," said Marchionne. "If we don't acquire the confidence of the financial markets, the future of Europe is doubtful. We need to get serious -- really serious."
German Chancellor Angela Merkel and International Monetary Fund Managing Director Christine Lagarde discussed late Tuesday efforts to solve the European debt crisis and the situation in Greece, a Merkel spokesman said.
"The chancellor and the IMF chief again declared their support for the goal to sustainably strengthen growth and employment in Europe," Steffen Seibert said.
Marchionne, widely recognized for turning around Fiat to become one of the industry's fastest-growing companies until the eurozone crisis, was instrumental in the Italian automaker's forming a strategic alliance with then-ailing Chrysler in 2009.
Less than two years later, Chrysler returned to profitability and repaid all its U.S. and Canadian government loans. Sales soared 26.2 percent for 2011 and 37.1 percent in December, the company said.
By contrast, Fiat, whose brands include Alfa Romeo and Ferrari, has struggled under the increasingly severe eurozone crisis. Its sales dropped 12 percent in the first 11 months of 2011 compared with a year earlier, the company said.
"Making a forecast in this crisis is impossible," Marchionne said. "We need to understand the uncertainty of the time we're living in."
Fiat is Chrysler's largest shareholder, at 58.5 percent, and plans to merge with the U.S. automaker by 2014.
Due to the European crisis, Marchionne said Tuesday he might bring on a third partner before the Chrysler merger, but refused to say what automakers he was considering.
"I obviously continue to watch the developments in Germany," he said.
General Motors Co.'s Opel auto brand is headquartered in Ruesselsheim, Germany. GM has insisted it has no intention of selling. Opel is one of Europe's largest automakers.
Referring to 2009's overhaul that many U.S. companies underwent, Marchionne bemoaned, "Europeans have always wanted the comfort of leaving things the way they are."