Egyptian police and protesters clashed in central Cairo early on Tuesday after fights broke out between supporters of ousted Islamist President Mohamed Mursi and locals angered when they tried to block major thoroughfares crossing the River Nile.
The MENA state news agency said at least 22 people were injured in the violence, which began just after 9pm on Monday and lasted into the early hours of Tuesday.
The clashes were smaller and more localised than the earlier deadly unrest since Mr Mursi was deposed by the military on 3 July, and most of Cairo was not affected, Reuters reports.
Despite that, scenes of running street battles close to the Egyptian Museum, one of the country's main tourist attractions, may raise further concerns about stability in the Arab world's most populous country.
"I've had enough of this chaos," Ashraf Mohamed, who watched the clashes from a distance, said. "Egypt is just rubbish."
Young men, their mouths covered to protect them from tear gas, threw stones at police and shouted pro-Mursi and anti-military slogans, as well as "Allahu Akbar" (God is greatest).
Military helicopters hovered overhead and police vans were brought in to quell the trouble but when that didn't work, dozens of riot police moved in. Medics treated men with deep gashes to their eyes and faces nearby.
Mr Mursi's frustration echoed the view of millions of Egyptians who rallied for his resignation on 30 June. The military said it deposed him to fulfil the wish of the people. Mr Mursi's Muslim Brotherhood movement said it was a coup.
"It's the army against the people, these are our soldiers, we have no weapons," said Alaa el-Din, a 34-year-old computer engineer, clutching a laptop. "The army is killing our brothers, you are meant to defend me and you are attacking me. The army turned against the Egyptian people."
Egypt has become increasingly polarised by the crisis, but one thing the two sides share is a deep mistrust of the United States and its perceived role in the unrest.
No desire to meddle - US
US Deputy Secretary of State William Burns told reporters in Cairo that Washington had no desire to meddle in Egypt, which it supports with $US1.5 billion in aid each year, most of which goes to the military.
"Only Egyptians can determine their future," Mr Burns told reporters at the US embassy. "I did not come with American solutions. Nor did I come to lecture anyone. We will not try to impose our model on Egypt."
Washington, never comfortable with the rise of the Islamist Brotherhood, has so far refused to say whether it views Mr Mursi's removal as a coup, which would require it to halt aid.
The Islamist Nour Party and the Tamarud anti-Mursi protest movement both said they turned down invitations to meet Mr Burns.
But a senior State Department official denied Mr Burns had been shunned. "I don't think we're losing influence at all," the US official said, adding Mr Burns was still in Cairo.
"I don't know what meetings he has but he has seen a range of people in Cairo in the interim government, in civil society ... so it's hard to say he has been spurned by both sides. I don't accept that is the case."