European Central Bank President Mario Draghi warned Tuesday that the eurozone economy has weakened unexpectedly amid rising headwinds originating outside the currency union, including an economic slowdown in China.

The comments reflect rising concerns among ECB officials that Europe’s six-year economic recovery could be undermined by a string of threats beyond its borders, from Brexit to tensions over international trade.

Europe’s economic slowdown, underlined earlier Tuesday by weak German growth figures for 2018, comes at an awkward time for the ECB: The central bank moved only last month to phase out a key stimulus tool, its €2.5 trillion ($2.85 trillion) bond-buying program, in a first step toward higher interest rates.

It could impact the ECB’s next policy steps, including a keenly awaited move to raise short-term interest rates for the first time since 2011. The ECB’s key policy rate is currently set at minus 0.4%, and policy makers have pledged to keep rates at that level at least though the summer.

“We’ve been receiving weaker data than expected now for a longer time than we had expected a few months ago,” Mr. Draghi told lawmakers in a speech at the European Parliament in Strasbourg, France.