Cairo (CNN) -- Supporters of deposed Egyptian President Mohamed Morsy attempted Friday to storm a media compound outside Cairo, burning tires and firing bird shot at security forces who responded by firing tear gas.
The clash came as the new military-backed government called for an end to two massive pro-Morsy sit-ins in Cairo that have drawn tens of thousands of protesters -- primarily Muslim Brotherhood supporters -- since the military ousted Morsy from office.
Egypt's military toppled Morsy, the country's first democratically elected president, on July 3 and quickly rounded up some of his top supporters. Morsy was just over a year into his presidency. He has not been seen publicly since being detained last month.
Morsy supporters have vowed not to end the protests until Morsy is returned to office, and they have been gearing up in recent days for a possible confrontation with the military after the government's warning.
As tensions rise across the country, so do fears of possible further violence in a country facing its worst crisis since the popular uprising that toppled Hosni Mubarak in 2011. Hundreds have been killed and thousands more wounded in clashes between Morsy's supporters and those opposed to his rule.
Upwards of 600 Morsy supporters targeted the Media Production City, a complex that contains multiple media outlets and production studios, because of what they called biased coverage of the coup.
On Nile TV, thick smoke could be seen rising from the complex, where some protesters had gathered near the front gate. Nile TV reported protesters were throwing Molotov cocktails at security forces, but a policeman at the clash told CNN he did not see anyone throwing Molotovs.
At least 31 people, described by authorities as "rioters," were arrested in the Media Production City melee, state-run media reported.
Ministry of Interior spokesman Gen. Hani Abdellatif said police had fired tear gas at pro-Morsy protesters outside the Media Production City.
As dusk fell Friday, cameras captured how packed the streets were in Cairo's Rabaa al-Adawiya and Nahda Masr squares as people shouted and waved flags. Egyptian state TV reported that security forces would cordon off the squares so people could only exit and not enter.
But Farida Mustafa, a spokeswoman for the Anti-Coup Prodemocracy Alliance, which organized the protests, told CNN that the group had seen no signs of the perimeter of Rabaa al-Adawiya being cordoned off.
Ministry of Interior spokesman Abdellatif also said there was no cordon and refused to confirm the state TV report.
Before the protests began, Morsy's defenders called for a million-man march from 33 mosques, but it's unclear whether the protest materialized.
In the hours leading to the protests, Egypt's Interior Ministry urged pro-Morsy protesters to leave the squares.
The demonstrations represent a threat to national security and traffic congestion, Information Minister Durriya Sharaf el-Din said Wednesday.
Interim Interior Minister Mohamed Ibrahim was authorized to take "all necessary measures to face these dangers and end them," el-Din said.
While protesters rallied in Cairo beneath a banner Friday that read, "Egypt against the coup," the U.S. State Department announced that Deputy Secretary of State Bill Burns is visiting the Egyptian capital.
Secretary of State John Kerry asked Burns to discuss with Egyptian leaders "the importance of avoiding violence and helping to facilitate a peaceful and inclusive political process," a release said.
Burns was in Egypt in mid-July visiting with interim government leaders.
The United States is concerned by reports that government critics in Egypt are being denied the right to peaceful protest, State Department deputy spokeswoman Marie Harf said Thursday.
"It's essential that the security forces in the interim government respect the right of peaceful protest, including the ongoing sit-in demonstrations," she said.
But Kerry's remarks Thursday in an interview with CNN's Pakistan affiliate, GEO TV, angered some Morsy supporters.
Asked why the United States is "not taking a clear position" on Morsy being deposed, Kerry replied, "The military was asked to intervene by millions and millions of people, all of whom were afraid of a descendance into chaos, into violence.
"And the military did not take over, to the best of our judgment so -- so far. To run the country, there's a civilian government," he said. "In effect, they were restoring democracy."
Muslim Brotherhood spokesman Gehad El-Haddad denounced Kerry's words and accused the Obama administration of being "complicit in the military coup."
"Is it the job of the army to restore democracy?" he asked.
He then asked whether Kerry would accept the removal of the U.S. government by the military if large protests took place there.
"Such rhetoric is very alarming. The American people should stand against an administration that is corrupting their values in supporting tyranny and dictatorship," he said.
A visiting African Union delegation went to the Rabaa al-Adawiya sit-in Thursday night.
Earlier, the group Human Rights Watch urged the government to order a halt to any immediate plans to break up the Muslim Brotherhood sit-ins by force and "deal peacefully with any problems arising."
"To avoid another bloodbath, Egypt's civilian rulers need to ensure the ongoing right of protesters to assemble peacefully, and seek alternatives to a forcible dispersal of the crowds," said Nadim Houry, deputy Middle East director at Human Rights Watch.
Houry warned that the number of protesters packed together in the squares means "hundreds of lives could be lost if the sit-in is forcibly dispersed."
The warning from Human Rights Watch echoed one issued by fellow rights group Amnesty International that warned any attempt by the government to break up the sit-ins was a "recipe for a bloodbath."
CNN's Schams Elwazer and Laura Spark-Smith contributed to this report.