HARARE, Zimbabwe — Allies of Zimbabwe’s president, Robert G. Mugabe, vowed on Tuesday that his government and the governing party would not be intimidated by the country’s military leaders after they threatened to intervene in a heated political feud.

But early Wednesday morning there were reports that a coup might be underway, and the United States Embassy on its website said that “as a result of the ongoing political uncertainty through the night, the ambassador has instructed all employees to remain home tomorrow.”

American citizens, the embassy said, “are encouraged to shelter in place until further notice.”

The streets of Harare, the capital, were largely empty as rain fell. Although the state broadcaster was said to have been seized by troops, normal programming continued and the only military presence outside was the usual detachment of guards.

Asked in a brief telephone interview about reports of a possible coup, the country’s information minister, Simon Khaya Moyo, said: “What can I say? I don’t know about that.” He did not elaborate.

The question of who will succeed Mr. Mugabe, 93, the nation’s leader since 1980, has long haunted Zimbabwe and its political class.

The long-simmering feud boiled over last week when Mr. Mugabe summarily expelled Vice President Emmerson Mnangagwa from the government and the governing ZANU-PF party, a move that was widely seen as clearing the path for Mr. Mugabe’s wife, Grace, as a possible successor.

Since his removal, the whereabouts of Mr. Mnangagwa, who like Mr. Mugabe was a veteran of the country’s struggle for independence, has been shrouded in mystery.

In a remarkable act of defiance, the commander of the Zimbabwe Defense Forces, Gen. Constantine Chiwenga, warned on Monday that “when it comes to matters of protecting our revolution, the military will not hesitate to step in.”

Neither the military nor Mr. Mugabe issued any public statements on Tuesday even as rumors of a possible coup surfaced on social media and in the streets of Harare. But Mr. Moyo, asserted in a statement that “the ruling ZANU-PF reaffirms the primacy of politics over the gun.”

Mr. Moyo, who is also the party’s national secretary for information and publicity, said the statement by General Chiwenga “suggests treasonable conduct on his part as this was meant to incite insurrection and violent challenge to constitutional order.”

“Purporting to speak on behalf of the Zimbabwe Defense Forces,” he said, “was not only surprising but was an outrageous vitiation of professional soldiership and his wartime record as high-ranking freedom fighter, entrusted with command responsibilities in a free and democratic Zimbabwe.”

Mr. Moyo’s statement, broadcast during the evening news hour on state television, came hours after a leader of the party’s Youth League made similar remarks at the ZANU-PF headquarters in Harare.

Kudzanayi Chipanga, the youth league’s secretary, suggested that military officers unhappy with the government should first return to civilian life if they wanted to become politicians.

“General Chiwenga and all those in the security sector who wish to engage in politics are free to throw their hats in the ring and not hide behind the barrel of the gun,” said Mr. Chipanga, who became a favorite of Zimbabwe’s first family after he helped organize a march last year in support of Mr. Mugabe’s leadership.

The youth league accused the general of siding with a faction loyal to Mr. Mnangagwa. The league has urged that Mrs. Mugabe be endorsed as the new vice president in a party conference scheduled for next month.