“Extensive investigations have taken place and some individuals are arrested," the spokesman, Gholamhossein Esmaili, said in remarks carried by Iran's official state-run news agency, IRNA.
Further information was not immediately available.
In a statement carried by state media on Saturday, Iran admitted that its military had "unintentionally hit" the jetliner with an anti-aircraft missile, adding that the plane was mistaken for a "hostile flight" after it turned toward a "sensitive military center." Iran had initially claimed the plane crashed due to a technical fault.
Iranian President Hassan Rouhani on Tuesday called for a special court to be set up to investigate the incident, which he called "a painful and unforgivable" mistake.
“The judiciary should form a special court with a ranking judge and dozens of experts,” Rouhani said in a televised speech. “This is not an ordinary case. The entire the world will be watching this court.”
Rouhani vowed that his administration will pursue the case "by all means," saying all those found responsible "should be punished."
"The responsibility falls on more than just one person," he said. "There are others, too, and I want that this issue is expressed honestly."
Over the weekend, throngs of protesters took to the streets of Tehran to express anger over the plane shootdown, which claimed the lives of 130 Iranian nationals who were among those on board. The crowds chanted "down with the deceptive government" and called for the release of all political prisoners. There were reports that Iranian security forces fired live rounds and tear gas to disperse the demonstrators at Tehran's central Azadi Square.
Iran's judiciary spokesman said Tuesday that "around 30 people have been arrested for taking part in illegal gatherings," according to the country's semi-official Tasnim News Agency.
"We have tolerance towards legal rallies," Esmaili added.
An airstrike, ordered by U.S. President Donald Trump, killed Iranian Maj. Gen. Qassam Soleimani near Baghdad International Airport in Iraq on Jan. 2. Soleimani had led the elite Quds Force of Iran's Islamic Revolutionary Guard Corps in operations throughout the region over the past 20 years, backing Syrian President Bashar al-Assad and supporting Shiite militia groups in Iraq, including against U.S. troops during the Iraq War. The U.S. Department of State has said that Soleimani's forces are responsible for the deaths of hundreds of American troops because of the kind of explosive devices they helped bring to Iraq. The United States designated Soleimani a terrorist in 2011 under then-President Barack Obama.
Iran called Soleimani's killing an "act of war." However, the Trump administration has argued that Soleimani's death was critical to thwarting "imminent attacks" that the Iranian commander was helping to plot against U.S. personnel in the region. The administration has provided no evidence of those threats.