Tehran's fourth step to reduce its commitments to the 2015 landmark nuclear deal.
In a speech broadcast live on TV, Rouhani said the Atomic Energy Organization of Iran (AEOI) will be ordered to begin the gas injection process at the Fordow nuclear facility - where 1,044 centrifuges are installed - under the supervision of the International Atomic Energy Agency (IAEA) on Wednesday, reports Press TV.
He, however, reaffirmed that all actions Iran has so far taken to reduce its commitments under the nuclear deal remain reversible.
The President said Iran was ready to resume its nuclear commitments when the remaining parties to the deal, officially called the Joint Comprehensive Plan of Action (JCPOA), fulfil their end of the bargain.
Iran, he added, cannot continue to uphold its side of the agreement unilaterally.
President Rouhani further expressed Iran's readiness to restart nuclear talks with member states of the P5+1 group - the US, France, Britain, Germany, Russia and China - if Washington returns to the deal and removes all the "wrong, cruel and illegal" sanctions it has re-imposed on Iran after abandoning it last year.
On the first anniversary of the US withdrawal from the deal on May 8, 2019, Tehran decided to reduce its commitments to the JCPOA and set a deadline for Europeans to remedy breaches, said the state-run IRNA news agency.
Tuesday's development comes after the US on Monday imposed sanctions on nine Iran including Chief Justice Ebrahim Raisi, Khamenei's second son Mojtaba Khamenei, senior adviser to the supreme leader in international affairs Ali Akbar Velayati, and Armed Forces Chief of Staff Mohammad Bagheri.
Also on Monday, Iran officially started injecting gas into advanced IR-6 centrifuges through a ceremony at Natanz Nuclear Facility.
Tuesday will be the fifth time that Tehran has rowed back on its nuclear commitments.
( With inputs from IANS )