LONDON — Their bromance once made headlines. But on Tuesday, it was clear that the days of President Trump and President Emmanuel Macron of France trading cheek kisses and clasping hands were gone.

On the sidelines of a gathering for the 70th anniversary of NATO, Mr. Trump took his one-time friend to task, denouncing comments Mr. Macron made last month criticizing the American president’s leadership of NATO, and calling into question several of the French leader’s policies.

Mr. Trump is known for trying to build personal relationships with his counterparts, but he also has a penchant for public feuds, fueled in part by his off-the-cuff approach to the news media and his regular Twitter rants.

And Mr. Macron is just one of a handful of one-time buddies whose initial coziness with Mr. Trump has turned cold.