In Cairo, police used tear gas against hundreds of Morsi supporters who had gathered in front of one of the capital's presidential palaces. Gunshots could be heard as well.
US State Department spokeswoman Jen Psaki, who noted that police also used water cannons to disperse the "peaceful" protesters, attributed the violence on the new anti-demonstration law.
"The United States is concerned by the troubling effects of Egypt's recently passed demonstrations law," she said.
Psaki pointed to report that demonstrators were beaten and dropped in the desert by authorities.
Also Read
"Limiting freedom of assembly, association and expression will not move Egypt's political transition forward."
Psaki also urged demonstrators to remain non-violent when holding protests.
The latest unrest came as Egypt's Muslim Brotherhood went ahead with protests it has organised after weekly prayers ever since the military ousted Islamist president Mohamed Morsi on July 3.
Protesters retaliated by throwing stones and burning tires in Mohandessin, officials said.
Other protests were dispersed in second city Alexandria, as well as in Suez, Mahallah and Qena, but details were sketchy.
At least 183 people were arrested nationwide, including 106 only in Cairo, the interior ministry said, and eight people were wounded.