Emerging economies have relied on global trade and supply chains to boost their growth.
The European economy has been facing various challenges this year.
"As laid out in the ECB's forward guidance, monetary policy will continue to support the economy and respond to future risks in line with our price stability mandate", she added. "And to some extent, this is what we saw in the euro area after the crisis", she said.
The eurozone debt crisis would have been much worse if not for the strong export demand for European goods and services. "But it also suggests that the high rates of trade growth that we are used to seeing are no longer an absolute certainty", Lagarde warned.
It would also help those national economies that needed to rebalance to do so more easily and in turn create greater economic resilience against any downturn.
While Lagarde's speech focused on fiscal policy rather than specifics about monetary policy, she has previously said the European Central Bank plans to continue its accommodative stance of cheap credit, record-low interest rates and massive bond purchases to stimulate the economy and drive up stubbornly low inflation.
Traditionally, ECB presidents talk about monetary policy, leaving elected leaders to manage their own economies and how to spend the cash in their coffers.
Lagarde is picking up where her predecessor Mario Draghi left off.
Her remarks about investment echoed those by the Organisation for Economic Co-operation and Development (OECD) which on Thursday also urged governments to loosen the purse strings.
At a time when "uncertainty abounds" and the conventional wisdom in diplomacy and economics was being "challenged", Europe "must consider its place in the world and reset its ambitions", argued the European Central Bank's new President.
Those would bring allow monetary policy, the ECB's remit, to achieve its goals more quickly and fewer side-effects, she said.
Lagarde became the ECB's first female chief at the beginning of November and the fourth since it was founded in 1988, having previously served two terms as the head of the International Monetary Fund (IMF). The policy package that the European Central Bank rolled out in September, including an interest rate cut and a massive bond-buying program, has been drawing mixed responses from the market and the political circles.
But the measures drew howls of protest from some council members who said they were too heavy-handed and would deepen the pain for eurozone banks already struggling to make a profit amid historically low-interest rates.