Treasury Secretary Tim Geithner warned Americans of "complacency" as the U.S. economy begins to show green shoots of recovery during a forum in New York City Monday morning.

"The key thing is that broad concern in the markets about the possibility of a deeper, more protracted, global economic dramatically diminished," Geithner told Time magazine's Richard Stengel as part of the Time Warner Economic Summit. "And that has helped provide some stability and economic activity."

But the secretary cautioned against too much optimism.

"It's very early, still. We don't want complacency to set in," he said. "This process of repair and recovery is going to take time; it's going to be uneven."

Geithner defended the Obama administration's work to help stimulate an economic recovery. He also characterized healthcare reform as a necessary part of strengthening the country's long-term economic future -- as long as it's deficit-neutral over the long run.