People gather at a government-organized march to show support for Mojtaba Khamenei, the new supreme leader in Iran, at Enghelab Square in Tehran on Wednesday. | Arash Khamooshi / The New York Times WASHINGTON/DUBAI/ISLAMABAD – U.S. President Donald Trump discussed how to mitigate the impact of a possible monthslong U.S. blockade of Iran's ports with oil companies, a White House official said on Wednesday, as the U.S. renewed its calls for other nations to help open the Strait of Hormuz. Tuesday's talks with oil executives followed a deadlock in efforts to resolve the conflict, which has led the United States to try to squeeze Iran's oil exports with a naval blockade aimed at forcing it to reopen the strait to shipping. As Washington and Tehran traded public threats, mediator Pakistan was trying to avoid an escalation while the ​two sides exchange messages on a potential deal, a Pakistani source said on Wednesday.…