PARIS — Xavier Denamur is used to bustling between the five popular bistros he owns in the Marais neighborhood of central Paris, managing a team of nearly 70 waiters and chefs and keeping tabs on the phalanx of patrons who crowd his tables, elbow-to-elbow, year round.

But on Monday, Mr. Denamur, 57, was scrambling to deal with a situation that he said resembled wartime conditions: overseeing the abrupt closure of his businesses as President Emmanuel Macron prepared to move France to a quarantine. It was soon official: The quarantine will start at noon Tuesday.

By midnight, Mr. Denamur would have to empty his refrigerators of almost €20,000 worth of chèvre cheese, boeuf bourguignon, pâté and other delicacies that would spoil by the time any quarantine ended, and would now have to be given away.

“We knew there would probably be a shutdown, but I didn’t think things would happen so fast,” he said, pressing two cellphones to his ears as he and a handful of employees hurried to empty refrigerators and wipe the bistros down before shuttering indefinitely.