Following Trump's remarks on Sunday that the US might not be bound by its longstanding one China policy "unless we make a deal with China having to do with other things, including trade", Ayrault warned him to "Watch out for China".
"It's a big country," he commented on France 2 television. "You can have disagreements with China but you don't talk like that to a partner."
"It's not very smart if China feels that the unity of China is questioned," the minister said.
Taiwan president's call
In a breach of previous US diplomatic practise, Trump last week accepted a phone call from Tsai Ing-wen, the president of Taiwan, which styles itself the Republic of China while Beijing regards it as a breakaway province.
Chinese Foreign Minister Wang Yi on Monday warned Trump that if he threatened the one China policy "they are lifting a rock only to drop it on their feet".
Trump's team 'unusual'
Ayrault said that Trump's administration, which is due to take office on 20 January, should be "judged by results", declaring it an "unusual team" after an "unusual election".
"We'll have to pay attention but it is to be hoped that over time the new team will have learnt enough to manage an uncertain mandate with calm and responsibility," he commented.
In the same interview Ayrault called for UN observers to be allowed to oversee the evacuation of the Syrian city of Aleppo.