The French economy is looking perkier. Eurozone unemployment, at 8.2 percent, is lower than it has been for around a decade. Wages in the common currency area are rising after years of meager growth.

But the list of risks is growing. The economy of Turkey, an important trading partner, is slowing, and that country’s central bank had to raise interest rates sharply on Thursday. Talks with Britain to negotiate an amicable divorce with the European Union are deadlocked. And German car exports slumped in July, probably because buyers are unsettled by the trade war, analysts say.

Trade is easily the biggest worry for European companies. For the moment, an uneasy truce prevails between Europe and the United States on trade. Mr. Trump and Jean-Claude Juncker, the president of the European Commission, agreed after a meeting in July not to impose more punitive tariffs on each other while they try to negotiate a broad trade deal.

But European political leaders and business managers are nervous that the American leader could grow restive if the talks do not produce quick results — and they probably will not. The European Commission is methodical in its approach, and hamstrung by the need to get approval from its 28 member states.

“There is really nothing the union can do to expedite its decisions on trade,” said Mujtaba Rahman, managing director in London at Eurasia Group, a political consultancy.

United States tariffs on steel and aluminum imports remain in place, raising prices and disrupting intricate supply chains. The Commerce Department continues to examine whether foreign-made cars are a threat to national security, a process that would create the legal foundation for the 25 percent tariffs on auto imports that Mr. Trump has threatened.

Mr. Trump seems to thrive on keeping people guessing, but businesses hate uncertainty. As long as the Damocles sword of Trump tariffs hangs above the eurozone, companies will be hesitant to buy new machinery or expand operations.