The G20 group of finance ministers have said trade tensions could undermine the global economy.
They called for greater dialogue to reduce the risk after a tense, two-day meeting in Argentina.
The summit comes as the US ramped up trade tensions on Friday, saying it was ready to slap tariffs on all $500bn of imports from China.
France's finance minister, meanwhile, said the EU should not negotiate trade with "a gun to its head."
In a joint statement, the G20 ministers said risks to growth "over the short and medium term have increased. These include rising financial vulnerabilities, heightened trade and geopolitical tensions."
"International trade and investment are important engines of growth," they said, adding that they "recognise the need to step up dialogue and actions to mitigate risks and enhance confidence."
The G20 summit comes as a trade war has escalated in recent weeks after the US opened fire on 6 July with tariffs on $34bn of Chinese goods.
The US has since listed another $200bn worth of Chinese products to be targeted and has threatened tariffs on an even greater amount.
US President Donald Trump also described the EU as a "foe" on trade last week.
French Finance Minister Bruno Le Maire warned that a trade war was now a reality at the G20 summit. He said the current US trade policy of imposing unilateral tariffs was based on "the law of the jungle".
But US Treasury Secretary Steven Mnuchin defended the tariffs and urged the EU and China to open their markets to allow free competition.
The US has large trade deficits with both the 28-member EU and China.
Given the US buys nearly four times as much from China as it sells to them, analysts fear it could seek alternative ways to get back at the US.
The two-day summit in Buenos Aires brought together finance ministers and central bankers of the world's top 20 economies.