A Lebanese crisis group of ministers met on Saturday to discuss a deepening diplomatic rift with Saudi Arabia.
The kingdom has expelled Lebanon's envoy to the Gulf state and banned all Lebanese imports.
Richard Michaels, deputy head of the U.S. mission in Lebanon, joined the crisis meeting, a U.S. Embassy spokesperson said, declining to comment further.
The row over critical comments made by Lebanese Information Minister George Kordahi about the Saudi-led military intervention in Yemen threw the government into a new crisis amid calls for Kordahi's resignation.
If Kordahi resigns, ministers backed by the heavily armed Hezbollah group and its Amal ally could follow suit at a time when the government is already paralysed by a dispute over an inquiry into the August 2020 Beirut blast.
Prime Minister Najib Mikati asked Kordahi on Friday evening to consider Lebanon's "national interest" but stopped short of asking for his resignation.
A group of former Lebanese prime ministers called on Saturday for Kordahi to resign, saying his comments had inflicted a strong blow to relations with Gulf Arab nations.
Fouad Seniora, Saad al-Hariri and Tammam Sallam said in a statement that Kordahi's remarks "harmed Lebanon's supreme national interest".
Kordahi has been publicly backed by Hezbollah and has declined to apologise or resign over the comments, which have dealt the worst blow to Saudi-Lebanese relations since Hariri's 2017 detention in Riyadh.
The minister's political patron, Suleiman Frangieh of the Hezbollah-allied Marada Movement, told a news conference that he had refused an offer by Kordahi to resign and would not name a successor to Kordahi should he do so.
The crisis risks widening to more Gulf states, with Bahrain also asking Lebanon's ambassador to leave shortly after the Saudi decision.
The Arab League said in a statement on Saturday it was concerned about the souring of Lebanese-Gulf relations and appealed to Gulf countries "to reflect on the measures proposed to be taken...in order to avoid further negative effects on the collapsing Lebanese economy".
Arab League Secretary-General Ahmed Aboul Gheit expressed "deep concern and regret over the rapid deterioration in Lebanese-Gulf relations...," the statement said.
Saudi Arabia has also recalled its ambassador to Lebanon for consultations.
Mikati has been hoping to improve ties with Gulf Arab states strained for years because of the influence wielded in Beirut by the Iran-backed Hezbollah.
In April, Saudi Arabia banned all fruit and vegetable imports from Lebanon, blaming an increase in drug smuggling.
The ban added to the economic woes of Lebanon, already in the throes of one of the most profound financial crises in modern times.