During the funeral processions, charged up Iranians joined their supreme leader in accusing regional rival Saudi Arabia of involvement in the twin bombings.
Thousands packed Tehran's streets on Friday to mourn the victims of two suicide bomb and gun attacks, and joined their supreme leader in accusing regional rival Saudi Arabia of involvement in the assaults.
People in the crowd chanted "Death to Saudi Arabia" alongside the more customary "Death to America" and slogans against Israel, as they reached out to touch coffins wrapped in flags and covered in flowers.
Bombers and gunmen killed 17 people in Iran's parliament and near the mausoleum of the Islamic Republic's founder, Ayatollah Khomeini, on Wednesday, in rare strikes on the capital that exacerbated regional tensions.
Daesh claimed responsibility for the attacks.
Iran's Supreme Leader Ayatollah Ali Khamenei, in a message read at the funeral, said the raids would increase "hatred for America and its stooge Saudi Arabia."
However, Saudi Arabia has denied these accusations and said it was not involved.
So far 41 suspects linked to the Tehran attacks have been arrested, Iran's Intelligence Ministry says.
Intelligence Minister Mahmoud Alavi told state TV on Friday several suspects linked to the attacks had been arrested around the country.
His ministry said two had been detained in the western Iranian province of Kermanshah. "Some terrorist cells also have been dismantled," it added.
Two Sunni militant groups, Jaish al Adl and Jundallah, have been waging an insurgency in Iran, mostly in remote areas, for almost a decade.