"If a regime or a government is involved in the Natanz incident, Iran will react decisively," said Foreign Ministry spokesman Abbas Mousavi.
The spokesman explained that experts from the Atomic Energy Organization of Iran and the Secretariat of the Supreme National Security Council had presented explanations on the incident.
“After summarizing, a full report will be presented in this regard and then, we will take the necessary actions in accordance with the findings that will be made after the investigation,” said Mousavi.
The spokesman additionally stressed that Iran would continue to cooperate with the IAEA.
A number of explosions have impacted Iran's infrastructure, industry and nuclear sites in recent weeks. It is unclear if there is any connection between the various incidents and Iran has referred to most of the incidents as accidents.
Israel was behind the explosion and fire at the Natanz nuclear complex caused by a "powerful bomb," a Middle Eastern intelligence official with knowledge of the incident told The New York Times.
Israel has worked to disrupt Iran's nuclear program in the past, including the Stuxnet cyberattack discovered in 2010, which targeted Iran's nuclear centrifuges and was blamed on Israel and the US.
Former top Mossad official Haim Tomer told 103FM last week that he was not aware of Israel being responsible for the explosion at Natanz, although the "substantial damage" caused in the incident showed that "there's an operational capability here."
Iranian reports originally referred the explosion as an "incident" without providing further details. Iran's top security body announced earlier this month that the cause of the incident at Natanz had been determined and would be announced later.
Some Iranian officials have said the explosion may have been caused by cyber sabotage, with one warning that Tehran would retaliate against any country carrying out such attacks.
An Iranian official has confirmed that the incident impacted Iran's nuclear program, but promised to repair the damage.
"The incident could slow down the development and production of advanced centrifuges in the medium term... Iran will replace the damaged building with a bigger one that has more advanced equipment," Iranian Atomic Energy Organization spokesman Behrouz Kamalvandi said, according to the IRNA state news agency.
Experts estimate that the explosion has caused large setbacks to Iran's nuclear program.
Reuters contributed to this report.