PARIS — A year ago, no one would have envisioned President Emmanuel Macron of France as the public face of Western diplomacy in the Middle East. But that is not the case anymore.

President Trump’s decision this past week to recognize Jerusalem as the capital of Israel, his anti-Muslim tweets and his State Department staffing cuts have signaled to many a retreat of American diplomacy.

That has made room for those who want to expand their presence on the world stage, Mr. Macron among them. He has quickly embraced a more visible role in the Middle East, especially as Britain and Germany have become more deeply preoccupied with domestic politics.

Mr. Macron called Mr. Trump two days ahead of the American president’s recognition of Jerusalem to tell him that France was “troubled” by the move.