Rafael Grossi
Rafael GrossiLev Radin/Sipa USA via Reuters Connect

Rafael Grossi, head of the International Atomic Energy Agency (IAEA), said on Monday he is concerned about Israel possibly targeting Iranian nuclear facilities, Reuters reported.

Grossi said Iran closed its nuclear facilities on Sunday over "security considerations" and that while they reopened on Monday, he kept IAEA inspectors away "until we see that the situation is completely calm."

"We are going to resume tomorrow," Grossi told reporters in New York. "This has not had an impact on our inspection activity."

Asked about the possibility of an Israel strike on Iranian nuclear facilities, Grossi replied, "We are always concerned about this possibility." He urged "extreme restraint."

The IAEA regularly inspects Iran's main nuclear facilities like its enrichment plants at Natanz that are at the heart of the country's nuclear program.

Grossi’s comments came amid speculation that Israel will retaliate for Iran’s drone and missile attack on Saturday night.

The Wall Street Journal reported on Monday that American officials believe Israel is preparing to respond to Iran's massive assault in the near future.

IDF Chief of Staff Herzi Halevi visited the Nevatim Airbase on Monday, two days after the base was damaged in the Iranian missile and drone attack, and said that the Iranian attack will be met with a response.

Meanwhile, Iran’s Deputy Foreign Minister, Ali Bagheri Kani, warned Israel against retaliating, saying a response to an Israeli retaliation “will not be measured in days and hours, but in seconds.”