"We have intelligence that Saudi Arabia is actively engaged in promoting terrorist groups on the eastern side of Iran, in Baluchistan", Mohammad Javad Zarif said on the sidelines of a conference on peace mediation in Oslo.
Promoting security in neighboring countries and the wider region is a foreign policy priority of the government in Tehran and the security of all Middle East nations, including Saudi Arabia, is important for the Islamic Republic, says the foreign minister.
Two days later, suicide bombings and shootings in Tehran killed 17 people.
The Iranian leader also said the U.S. and Saudi Arabia are in partnership when it comes to funding Sunni militants.
Following the incident, the so-called Abdullah Azzam Brigades claimed responsibility for the bombings.
He also blasted any attempts at building bridges with the United States, saying: "America is a terrorist country and backs terrorism. therefore, we can not normalise ties with such country".
On Tuesday, commander of Iran's Islamic Revolution Guard Corps (IRGC) said that Saudi Arabia has been behind June 7 terrorist attacks in Tehran. High on the list of reasons for breaking ties, Saudi Arabia named Qatar's friendly ties with Iran and Hamas.
He gave no further details, but other officials said that four other alleged members of the gang had been killed in the southern Iranian province of Hormozgan, home to a substantial Arab minority.
President Donald Trump has previously slammed the Islamic regime, warning its nuclear ambitions are a threat to the world.
Iran, which has been accused of exposing sectarian fault lines in the region, especially in Yemen, Syria and Iraq, tried to soften its rhetoric as Rouhani said there should be greater unity between Shiites and Sunnis and that they had coexisted side by side peacefully for hundreds of years. On Friday, however, he turned his wrath for the attacks on the United States and Saudi Arabia.
He mentioned that victims of terror in Iran include people of different ethnic and religious groups as terrorists have been targeting them as "Iranians" and not as individuals belonging to a certain ethnic or religious group.