The headquarters of the pro-Kurdish Democratic Peoples’ Party (HDP) was attacked on Thursday night.
Security camera footage posted on social media showed three attackers repeatedly throwing rocks at the HDP headquarters in Ankara at around midnight.
Police assigned to protect the building had failed to properly intervene, the party said in a statement.
Recent inflammatory comments by Turkish interior Minister Süleyman Soylu were to blame for the incident, it said.
On Thursday, Soylu said allegations he had links with organised crime were a political smear promoted by the “HDPKK”, an acronym compounding the abbreviations of the HDP and the outlawed Kurdistan Workers’ Party (PKK).
Earlier in the day, convicted organised crime boss Sedat Peker claimed the interior minster had helped protect him from police investigation.
The attack on its offices came after Soylu had sought to deflect blame for being ”exposed by the mafia and its dark partners” onto the opposition, the HDP said.