Several people have been detained in Iran over the accidental shooting down of a Ukrainian passenger plane with a missile.
Judiciary Spokesman Gholamhossein Esmaili said investigations into the incident were continuing, but provided no details.
President Hassan Rouhani said the probe would be overseen by a “special court”.
For the first three days after the crash, Iran denied its armed forces had shot down the Boeing 737-800 and suggested there had been a technical failure.
Most of the victims were Iranian and Canadian citizens.
The admission of responsibility provoked widespread anger in Iran, and protesters took to the streets in the capital and several other cities, to denounce government lies and the clerical leadership, including Supreme Leader Ayatollah Ali Khamenei.
Judiciary Spokesman, Esmaili told a news conference in Tehran that the judiciary would “investigate the causes and direct impact of the incident”.
He also added they will investigate the extent to which US warmongering caused this event.
Mr Esmaili also said about 30 people had been arrested for “taking part in illegal gatherings” – an apparent reference to the recent anti-government protests.
In a televised speech, President Rouhani said the judiciary would assemble a special court with a high-ranking judge and tens of experts to oversee the probe.
He had on Tuesday said the crash of a Ukrainian passenger plane was an “unforgivable mistake” by Iran’s military.
The President also that Iranian armed forces admitting their mistake is a good first step and assured the people that it will not happen again.
Mr Rouhani also said he wanted relevant officials to explain publicly why it took days for the authorities to disclose that missiles were fired at flight PS752.