Pope Leo said he has seen the letter from the parents of more than 100 children killed in the strike, which a preliminary inquiry found resulted from a mistake by the U.S. military.
The last-minute scuttling of the trip to Pakistan was the latest sign of how far apart the two sides are on reaching a deal to end the Iran war.
The fragile truce in Lebanon was extended after talks in Washington this week but has come under threat as Israel and Hezbollah have traded attacks.
President Trump withdrew from the Obama-era nuclear accord in 2018, saying it was the worst deal ever. But Iran responded with an enrichment spree that haunts the negotiations to this day.
In guidance to immigration officers, the administration describes participating in pro-Palestinian protests and criticizing Israel as “overwhelmingly negative” factors.
President Trump has outsourced much of his diplomacy to others, while Mr. Rubio focuses on his second job as national security adviser.
Iran’s foreign minister has already arrived in the country, state media reported. He was believed to be carrying a written response to a U.S. proposal to end the war.
The move was intended to ensure the flow of fuel in the United States, but some economists say it might reduce gas prices for consumers only a small amount.
Secretary of State Marco Rubio said that while the players were welcome, anyone accompanying them who has links to the Iranian military would be denied entry.
The Pentagon’s rush to rearm its Mideast forces makes it less ready to confront potential adversaries like Russia and China, administration and congressional officials say.