French Finance Minister Michel Sapin speaks during an interview with Reuters in his office at the Bercy Ministry in Paris, France, October 4, 2016. REUTERS/Jacky Naegelen

PARIS (Reuters) - Criticism of Europe by U.S. President-elect Donald Trump only serves to reinforce European solidarity, French Finance Minister Michel Sapin said on Tuesday.

Trump said German Chancellor Angela Merkel had made a “catastrophic mistake” with her open door policy on migration, according to an interview published on Sunday by German newspaper Bild.

“The more he (Trump) makes this sort of statement, the more Europeans close ranks,” Sapin told reporters, adding that such criticism was unacceptable. “The attack on the Chancellor is not an argument we can accept as Frenchmen or as Europeans.”

Asked whether Europe would have to react if the United States decided to slap a 35 percent tax on imports, Sapin said: “We will all have time to see whether there’s a difference between the content of a tweet and the laws that will be passed.”

Trump was quoted as telling Bild he would impose a 35 percent levy on German-made cars imported to the U.S. market, a plan that drew sharp rebukes from Berlin and hit automakers’ shares.

“I would tell BMW that if you are building a factory in Mexico and plan to sell cars to the USA, without a 35 percent tax, then you can forget that,” Trump said in remarks translated into German.