Iran's judiciary said Tuesday arrests have been made for the accidental downing of a Ukrainian passenger plane that killed all 176 people aboard just after takeoff from Tehran last week.

The announcement involving UIA Flight PS752 came amid an upswell of anger and protests by Iranians in recent days over last Wednesday's deadly crash and apparent attempts by senior officials in Iran to hide the cause.

Iran, which initially dismissed allegations a missile had brought down the plane, acknowledged only on Saturday — days after and in the face of mounting evidence — that its Revolutionary Guard had shot down the plane by mistake as the force braced for a possible military confrontation with the United States.

Judiciary spokesperson Gholamhossein Esmaili said "extensive investigations have taken place and some individuals are arrested." His statement on the judiciary's website did not say how many individuals had been detained or name them.

Iran's president on Tuesday also called for a special court to be set up to probe the downing.

"The judiciary should form a special court with a ranking judge and dozens of experts," President Hassan Rouhani said in a speech televised in Iran. "This is not an ordinary case," he said, noting that the world will be watching.

Rouhani called the incident "a painful and unforgivable" mistake, and promised his administration would pursue the case "by all means."

"The responsibility falls on more than just one person," he said, adding those found culpable "should be punished.

"There are others, too, and I want that this issue is expressed honestly," he said, without elaborating.

Iran shot down the plane as its forces were on alert for possible U.S. retaliation after Iran launched ballistic missiles on two military bases housing U.S. troops in Iraq. No one was hurt in that attack, which was carried out in response to the stunning killing of Revolutionary Guard Gen. Qassem Soleimani in an American airstrike in Baghdad.

A woman attending a candlelight vigil Saturday to remember the victims of the Ukraine plane crash, talks to a policeman, at the gate of Amri Kabir University in Tehran, in photo released by ISNA, the Iranian Students' News Agency. (The Associated Press)

While Rouhani pointed to mistakes and negligence, he also repeated the government's line that the tragedy was ultimately rooted in U.S. aggression.

"It was the U.S. that made for an agitated environment. It was the U.S. that created an unusual situation. It was the U.S. that threatened and took our beloved [Soleimani]," he said.

Rouhani called the government's admission that Iranian forces shot down the plane a "first good step."

He said Iranian experts who retrieved the Ukrainian plane's flight recorder, or black box, have sent it to France for analysis.

The plane, en route to the Ukrainian capital of Kyiv, was carrying 167 passengers and nine crew members from several countries, including 82 Iranians, 57 Canadians — including many Iranians with dual citizenship — and 11 Ukrainians, according to officials. There were several children among the passengers, including an infant.

Gen. Amir Ali Hajizadeh, the head of the Guard's aerospace division, said over the weekend his unit accepts full responsibility for the shootdown. He said when he learned about the downing of the plane, "I wished I was dead."

The incident raised questions about why Iran did not shut down its international airport or airspace the day it was on alert for U.S. military retaliation.

Protesters detained in Iran

The shooting down of the plane and the lack of transparency around it have reignited anger at Iran's leadership. Online videos appeared to show security forces firing live ammunition and tear gas to disperse protests in the streets.

Also Tuesday, Iran's judiciary said 30 people had been detained in the protests and some were released, without elaborating further. An Iranian film director who'd called for protests in Tehran's Azadi, or Freedom, Square is among those released.

WATCH: Anger in Iran over downing of Flight 752

Anger over Iran shooting down Flight 752 is spilling into the streets as protesters fear retaliation. 1:59

Iranian authorities briefly arrested British Ambassador Rob Macaire on Saturday evening. He's said he went to a candlelight vigil to pay his respects for the plane victims, and left as soon as the chanting began and it turned into a protest.

Iran's Foreign Ministry summoned the British ambassador on Sunday to protest what it said was his presence at an illegal protest. Britain, in turn, summoned Iran's ambassador on Monday "to convey our strong objections" over the weekend arrest.