Macedonian police detained about 30 people Tuesday, including a former interior minister, former police officials and opposition conservative lawmakers over an invasion of parliament in April this year.
The public prosecutor's office said it issued an order relating to 36 people in connection with the attack by protesters that left more than 100 people injured.
Several MPs were beaten in the rioting, including the leader of Social Democrats, Zoran Zaev, who has since become prime minister.
The public prosecutor's office for organised crime and corruption said in a statement on Tuesday it had ordered an investigation into 36 people suspected of "terrorist endangerment of the constitutional order and security," which carries a minimum jail sentence of 4 years.
Former Interior Minister Mitko Chavkov, two former police officials, three lawmakers and protest leaders are among those detained.
The protesters had stormed the parliament after the country's opposition Social Democrat party and others representing Macedonia's Albanian ethnic minority voted for a new speaker.The protesters attacked journalists and lawmakers, including the opposition leader, Zoran Zaev, now Macedonia's acting prime minister.
The violence followed months of protests by nationalists opposed to a coalition deal between Zaev's Social Democrats and minority ethnic Albanian parties, which they alleged was a threat to national unity.
Ethnic Albanians make up around a quarter of Macedonia's two million people.
The storming of parliament, which met with international condemnation, erupted over the election of Talat Xhaferi, who is ethnic Albanian, as speaker.
The protesters alleged the vote was illegal.
The opposition VMRO-DPMNE party condemned the detentions and called for a protest later in the afternoon in front of the court building.
"VMRO-DPMNE is today under attack by the anti-state junta of Zoran Zaev," the party said in a statement. It said it considered the move as "an attempt to silence the opposition and break the resistance of the party against all anti-state policies that the government has implemented" since it gained power.
Macedonia's parliament elected a new center-left coalition government led by Zaev in May this year, ending a six-month political stalemate.