Six representatives from the opposition Cambodia National Rescue Party have been charged over Tuesday's violence between protesters and city security guards.
The charges, including incitement of rioting, carry up to 30 years in prison.
Among those charged and detained is Mu Sochua, a popular Rescue Party leader who also holds a US passport.
Hundreds of riot police were deployed along roadways near the court to prevent protesters from convening on the court Wednesday morning. No clashes were reported.
More than 50 people were injured in Tuesday's incident, many of them district security guards, when a peaceful protest turned violent. Witnesses said protesters had responded to violence and insults by Daun Penh district security guards and had acted despite calls from Mu Sochua and others to remain non-violent.
Rescue Party Vice President Kem Sokha told reporters Wednesday that mass demonstrations could be held to demand the release of the detained party members.
He also said that political negotiations between the ruling Cambodian People's Party and the opposition cannot be held while senior members of his party are in jail.
The Rescue Party has sought major election reforms following polls a year ago it says were marred by fraud.
Pro-opposition demonstrations in January turned violent, leading to the deaths of at least four people, as well as a ban on public assembly. The ban was strictly enforced, including at Freedom Park, a government-sanctioned assembly area in the middle of the capital.
It was at Freedom Park that Mu Sochua and other opposition leaders had led demonstrations against the assembly ban, including those that turned violent on Tuesday.
Mu Sochua was charged along with lawmakers-elect Keo Pearum, Men Sothavrin, Ho Vann and Real Camerin, as well as her assistant, Oeur Narith.
They have been charged under the Cambodian Criminal Code with "leading an insurrectional movement," "incitement to commit a felony," and "instigation to commit acts of violence."
The US on Wednesday called for their release.
"The US Embassy strongly condemns the violence that occurred at Freedom Park yesterday," embassy spokesman John Simmons told VOA Khmer by e-mail. "Progress toward a resolution of the current political impasse is only possible through peaceful and constructive dialogue. We call for the release of Mu Sochua and the other members of parliament in the spirit of political reconciliation."
Mu Sochua is meanwhile receiving consular services as an American citizen, he said.
