Iran will increase its level of uranium enrichment after Sunday (July 7) to whatever levels it needs beyond the 3.67 percent cap set in the landmark 2015 nuclear deal, Iranian President Hassan Rouhani said on Wednesday, according to the IRIB news agency.

Uranium refined to a fissile purity of 3.67 percent is deemed suitable for electricity generation and is the maximum allowed by the deal. Enrichment to 90 percent yields bomb-grade material.

If the remaining signatories of the nuclear deal with world powers do not fulfill their promises, then the Arak nuclear reactor will return to its previous activities after July 7, Rouhani said.

"From (July 7) onward with the Arak reactor, if you don't operate (according to) the programme and time frame of all the commitments you've given us, we will return the Arak reactor to its previous condition," said Rouhani.

Iran's reduction of commitments under the nuclear deal is not intended to strike a blow against the deal but to preserve the deal, he said, adding that Iran will remain committed to the nuclear deal as long as the other side stays committed to the nuclear deal.

Iran announced this week it has stockpiled more low-enriched uranium than is permitted under the accord, a move that prompted U.S. President Donald Trump - who withdrew the United States from the deal last year - to warn Iran was "playing with fire."

European co-signatories said on Tuesday they were "extremely concerned" by Tehran's apparent breach of the deal while Israel said it was preparing for possible involvement in any military confrontation between Iran and the United States.