Ghada Badrawy, 35, of Chantilly, center, and Tawfik Daoud, 41, of Fairfax, right, and others participate in a protest outside the White House on Saturday July 6, 2013. (Sarah L. Voisin/The Washington Post)

Zeinab Mansour, 70, a librarian from Chevy Chase, returned to her native Cairo two years ago to participate in the democratic revolution that toppled Egypt’s longtime dictator, Hosni Mubarak. Last year, the dual citizen voted in Egypt’s first free elections, which led to the presidency of Mohamed Morsi of the Muslim Brotherhood.

On Saturday, Mansour was out on the streets again, this time joining a rally in front of the White House to celebrate Morsi’s ouster by the Egyptian army Wednesday and to ask the Obama administration to support a second chance for democracy in her homeland after a year of turmoil and religious pressure under Morsi and his Islamist followers.

“I am here to fight for the promise of freedom, justice and dignity. I am here to ask Mr. Obama to respect the will of the Egyptian people,” said Mansour, who chanted slogans in Arabic along with about 100 other Egyptian immigrants in Lafayette Square. “We need a Nelson Mandela to bring Muslims and Christians together for the future of Egypt.”

But even as many members of the Washington area’s large, middle-class Egyptian American community welcomed Morsi’s overthrow, calling it a “revolution, not a coup,” others warned that the sudden power vacuum and ongoing violent clashes involving secular, Islamist and security forces could lead to wider religious and social conflict in the poor Middle Eastern nation of 90 million.

“This is a very, very dangerous situation,” said Nancy Okiel, an Egyptian Muslim and staff member at the nonprofit rights group Freedom House in the District. “I am not optimistic at all when I see people dying in the streets, and I don’t think the issue is whether there was a coup or not. The country is very divided, and no matter how it settles, a lot of lives will be lost first.”

The demonstrators, along with many online Egyptian American commentators, expressed frustration at the Obama administration’s cautious reaction to the unfolding events in Egypt. Many suspect that Washington seeks to restore stability in Egypt at the expense of popular demands. The administration, which provides huge amounts of aid to Egypt, accepted Morsi’s election but also has close ties to the army.

“A lot of people are very angry at President Obama, and what he said has been lost in translation,” said Samia Harris, who heads a private school in Woodbridge. “The Egyptian people want freedom, human rights, justice and respect for law, and we want Mr. Obama and his administration to listen to them. This was not a coup. It was a marching order from the Egyptian people.”

Among the most impassioned local opponents of Morsi are members of the Coptic Christian community, which has long been persecuted in Muslim-dominated Egypt. This week, some Coptic activists equated the Muslim Brotherhood with al-Qaeda and said they hoped Morsi’s ouster would help lead to the defeat of Islamic extremism.

“This was the first step to end political Islam and create a real civil society in Egypt — maybe even in the entire Middle East,” said Magdi Khalil, a Coptic activist from Northern Virginia who was at Saturday’s rally. “This is an historical chance to bring democracy and take action against the Islamist phenomenon everywhere.”

But other Copts said they feared that relatives and friends back home would suffer reprisals from Muslim Brotherhood supporters, who are highly organized and committed to the installation of an Islamic state. If they are shut out of power, some said, retaliatory violence and instability could spread.

“As happy as I am, I know this is not the right path,” said Mina Abdulmalek, 24, a Coptic activist who works at the U.S. Holocaust Memorial Museum. “All my friends and family are in Cairo. We are telling my sisters to stay home. They don’t wear headscarves, so it is easy to tell a Christian girl from a Muslim one.”

Some moderate Egyptian Muslims in the area joined Coptic groups in cheering the departure of Morsi, and some Copts said they preferred to identify themselves as Egyptians first at this time of national transition. One was Magid Gebra, 33, a researcher in Northern Virginia who joined a throng of excited people outside the Egyptian Embassy in the District on Wednesday, singing and chanting until he was hoarse.

“In January, 30 million people took to the streets to demand the ouster of Morsi. He ignored their demands, and now the military has sided with the people,” Gebra said. “This was the only way to get Egypt’s revolution back on track.”