A case against BNP and Jamaat-e-Islami activists was filed by Boalia Model Police Station Sub-Inspector Jahangir Alam early on Friday.
Inspector Mahmudur Rahman said eight persons were named in the case.
He added that 30-35 unidentified BNP-Jamaat activists were also made accused.
BNP’s Rajshahi city unit Vice President Bulbul is also a member of the party’s central committee.
It was alleged in the case that he instigated and directed the attack.
During a blockade called by BNP, activists of Jamaat attacked a Dhaka-bound convoy escorted by security forces in Rajshahi on Thursday afternoon.
They hurled 15-20 Molotov cocktails and bombs at trucks, buses and autorickshaws in the convoy, damaging at least 15 vehicles.
Three persons were injured in the attack.
President of Rajshahi College’s Islami Chhatra Shibir Sarwar Alam Siddiqui Joha was seen leading the attack.
The inspector said he was not named in the case even though he was seen in photos published by the media as leading the assault.
Meanwhile, a mobile court set in the police station on Thursday night sentenced nine arrested at the spot to two months in jail.
The inspector said Magistrate Sheikh Shamsul Arefin also fined them Tk 500 each. They will have to serve an additional seven-day jail term if they fail to pay the fines.
All of them, activists of BNP and Jamaat, confessed their involvement in the attack, he said.
They were sent to Rajshahi Central Jail on Friday morning, he added.