But the episode illustrated just how blurry the line is likely to be between the comments and actions of a President Trump and the interests he shares with scores of business associates he has cultivated around the world.

“Even if this was truly a social meeting and not a business one, there’s a cloud of doubt that hangs over it and will last for the next four years unless he sells the business outside of the family and places the assets in a true blind trust,” said Jordan Libowitz, a spokesman for Citizens for Responsibility and Ethics in Washington, a nonprofit legal watchdog group.

“When he makes foreign policy decisions that affect Dubai, will they be in the interest of the American people or in the interest of his business partnership?” Mr. Libowitz said. “Is he catching up with an old friend or ironing out a secret deal? We have no way of knowing.”

Mr. Trump canceled a news conference last month at which he had said he would provide details about how he planned to sever ties with his vast business empire and alleviate conflicts.

While he has noted, correctly, that anti-conflict laws will not apply to him as president, Mr. Trump said he would work to eliminate even the appearance of such inappropriate influence. He has rejected calls to liquidate his company and place the proceeds in a blind trust, as ethics experts in both parties have urged. He has said he plans to separate himself from the Trump Organization and leave his sons, Eric Trump and Donald J. Trump Jr., at the helm.