While the European Union is "willing to build bridges", Moscovici told reporters "we believe that targeting us is certainly inappropriate. and that we must act with the USA as allies - not foes but allies". Mr Trump, who frequently criticises Europe's 10 per cent vehicle tariffs, is also studying adding a 25 per cent levy on automotive imports, which would hit both Europe and Japan hard.
"We are waiting for the USA to take the necessary steps to get out of the trade war", said Le Maire.
"We refuse to negotiate with a gun to our head", Le Maire told reporters on the sidelines of the G20 meeting in Brazil on Saturday, according to French media.
European Commissioner for Economic and Financial Affairs Pierre Moscovici told reporters that the meeting was not tense, but produced little movement from entrenched positions on trade.
Mr Mnuchin's offer to the European Union and Japan - along with a renewed effort to jump-start stalled talks with Mexico and Canada to modernise the North American Free Trade Agreement - come as the U.S. and China are at loggerheads in an escalating trade dispute with no talks in sight.
The weekend talks in Buenos Aires came at a time of escalating rhetoric in the trade conflict between the United States and China, the world's largest economies, which have so far slapped tariffs on $34 billion worth of each other's goods.
Mr Mnuchin is not meeting formally with any Chinese officials at the G-20 meeting, but said that was because his normal counterpart, top Chinese economic adviser Liu He, is not attending.
He said G7 allies were taking seriously his calls to eliminate tariffs, non-tariff barriers and subsidies among the group, and the Trump administration would pursue such ideas in trade talks next week with European Commission President Jean-Claude Juncker in Washington.
"While all countries will ultimately be worse off in a trade conflict, the US economy is especially vulnerable", IMF Managing Director Christine Lagarde wrote in a blog post."Policymakers can use this G20 meeting to move past self-defeating tit-for-tat tariffs".
"This trade war will produce only losers, it will destroy jobs and put pressure on global growth".
Trump's metals tariffs prompted trade partners to retaliate with their own tariffs on US goods ranging from whiskey to motorcycles.
Mnuchin today told reporters he had not seen a macroeconomic impact on the U.S. from its tariffs on steel, aluminium and Chinese goods. "We are working to strengthen the contribution of trade to our economies".
He said the final communique would reflect the need for members, particularly in emerging markets that have been roiled by currency weakness, to undertake reforms to protect themselves against volatility.
Recently imposed United States tariffs will cost Germany up to €20 billion ($23 billion) in income this year, according to academic researchers at the Macroeconomic Policy Institute (IMK), which is part of the Hans-Böckler Foundation in Düsseldorf.
Mnuchin said he did not feel isolated at the G20, holding numerous bilateral meetings with officials, and arguing that Trump's trade stance was not based on protectionism, but on trying to make trade fairer.