President Rouhani, for his part, thanked Assad over the condolences and solidarity, stressing that the incident would not affect the steadfastness and resilience of the Iranian people, who have become more determined to counter terrorism.
The death toll from Wednesday's attacks on the Iranian parliament building and the mausoleum of Imam Khomeini, claimed by Daesh (ISIL) terrorist group, grew to 17 on Thursday.
Fazelian said seven of the individuals arrested had been nabbed in Fardis, in southern Alborz, and the remaining one had been apprehended in Karaj, the provincial capital. At least 17 people lost their lives and almost 50 others were wounded in the assaults, which involved shootings and blasts.
Tensions have been rising between conservative USA -allied Gulf Arab states, including the UAE, and non-Arab Iran over accusations that Tehran is meddling in the affairs of its Arab neighbours, a charge the Islamic Republic denies.
President Hassan Rouhani said on Friday that the terrorist attacks in Tehran on Wednesday were in fact vengeance against democracy.
The atrocities of ISIS in Tehran was condemned by Pope Francis who "laments this senseless and grave act of violence", and "assures the people of Iran of his prayers for peace".
The Interior Ministry in a statement increased the number of wounded to 52.