The U.S.-driven trade war has become the biggest "confidence killer" for the global economy, China's foreign ministry warned on Wednesday, saying the whole world would fight back if the United States continued to be "wilful."

Foreign ministry spokeswoman Hua Chunying told reporters at a regular press briefing that the United States is fabricating all kinds of justifications for its trade actions, including that of national security.

Earlier this month the United States and China slapped tariffs on $34 billion of each other's imports in an escalating trade tussle that has roiled financial markets.

U.S. President Donald Trump has threatened further tariffs unless Beijing agrees to change its intellectual property practices and high-technology industrial subsidy plans.

Trump has also hit European metal imports with tariffs and has threatened to curb car imports from Europe with a 20 percent duty.

"The U.S. trade war is not just with China but with the rest of the world. By regarding the rest of the world as adversaries, the U.S. has dragged the entire global economy into a place of danger," Hua said.

The European Commission last week cut its forecasts for the euro zone's economic growth this year, saying the main causes for the revision were trade tensions with the United States as well as higher oil prices.

China's economy grew at a slower pace in the second quarter, data on Monday showed, with Beijing's trade dispute with Washington challenging the growth outlook for the world's second-biggest economy.

"If the U.S. continues to be wilful, countries around the world will only harden their resolve to hit back," Hua said.