In July, the IMF forecast global growth at 3.3% this year, slightly below last year's 3.4%, as reported.
"Overall, we expect global growth to remain moderate and likely weaker than we anticipated last July," Lagarde told university students at the start of a two-day visit to Indonesia's capital.
Lagarde warned that such countries as Indonesia should "be vigilant for spillovers" from China's slowdown, tighter global financial conditions, and the prospects of a U.S. interest rate hike.
Lagarde also noted that China's economy has been slowing down, although not sharply or unexpectedly, as it adjusts to a new growth model.
"The transition to a more market-based economy and the unwinding of risks built up in recent years is complex and could well be somewhat bumpy," she said.
