However, the deal was contingent "on the understanding that as long as we are negotiating. we will hold off further tariffs, and we will reassess existing tariffs on steel and aluminum".
China has struck back with duties on soybeans and pork, affecting mid-western United States farmers in a region of the country that supported the president in his 2016 campaign.
US President Donald Trump accused China of targeting American farmers in a "vicious" way and using them as leverage to get concessions on trade, even as some farmers and farm-state lawmakers, including Republicans, blamed Trump, saying they would rather trade with no tariffs than share the $12 billion aid that Trump offered.
While EU officials had threatened immediate retaliation to any auto tariffs, and said they would not negotiate with Washington under duress, they seem to have chose to appease the irascible US leader. But others were wary, wondering whether it's realistic to expect Europe to buy more soybeans from the United States, as Juncker signaled, or to become "a massive buyer" of liquefied natural gas from the USA, as Trump declared. He hoped "free, fair and reciprocal trade is in our near future".
The tone was friendlier than it has been.
With the United States threatening to impose punishing new tariffs on European Union auto exports, Juncker said: "We are close partners, allies - not enemies". But we have to do it.
But he also cautioned that the U.S. is watching China's currency movements for any signs Beijing is manipulating the yuan.
The leaders agreed to "launch a new phase" in the relationship and "to work together towards zero tariffs, zero nontariff barriers, and zero subsidies on nonauto-industrial goods", Trump said.More news: Palestinian teenager jailed for slapping soldiers leaves prison
Where does this leave other disputes between the USA and its trading partners? The U.S. has imposed tariffs on the metals, again justifying the action on national-security grounds. The U.S. and European Union are now working to resolve their differences over steel and aluminum - but the tariffs are still in place.
France's Le Maire singled out this pledge as especially problematic, given deep concerns over the GMO's in U.S. soybean production that falls foul of European Union norms.
Whatever progress was achieved on Wednesday could provide some relief for U.S. carmakers.
Trump has enacted tariffs that have been criticized by farmers and manufacturers who warn a global trade war and retaliatory tariffs from countries like China, Mexico and Canada will damage their livelihoods. General Motors had slashed its outlook, and shares of Ford Motor Co. and auto parts companies had fallen.
In retaliating for USA tariffs, China targeted products from areas of the country that supported Trump during the 2016 election.
He later said the two would work toward resolving the steel and aluminum tariffs.
Mnuchin said there were no new developments on the dispute with China, which has been the target of most of Trump's trade policies.