U.S. Secretary of State Mike Pompeo speaks during a press briefing in Washington D.C., the United States, April 22, 2019. (Xinhua/Liu Jie)

WASHINGTON, July 7 (Xinhua) -- U.S. Secretary of State Mike Pompeo on Sunday warned that Iran's move to raise its uranium enrichment concentration would result in "further isolation and sanctions."

Earlier in the day, Iran announced that it is raising its uranium enrichment concentration beyond 3.67 percent, the limit set by the landmark 2015 international nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA).

"Iran's latest expansion of its nuclear program will lead to further isolation and sanctions," Pompeo said in a tweet, calling for other nations to restore the standard of no enrichment for Iran's nuclear program.

Iranian President Hassan Rouhani speaks during a meeting with Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan in Sochi, Russia, on Feb. 14, 2019. (Xinhua/Sputnik)

In May last year, the Trump administration unilaterally abandoned the JCPOA, which was inked by Iran with Britain, China, France, Germany, Russia, and the United States in 2015.

Under the deal, Iran was required to limit its level of uranium enrichment at 3.67 percent, and to keep its stockpile of low-grade enriched uranium no more than 300 kg.

Atomic Energy Organization of Iran (AEOI) said that the rise of the purity of uranium enrichment from current 3.67 percent to the higher level aims at "meeting the needs of fuel for Iran's power plants."

On Saturday, Ali Akbar Velayati, an adviser to the Iranian supreme leader, said that Iran might increase the purity of its enriched uranium to five percent as a part of Tehran's decision to reduce its commitments under the 2015 nuclear deal.

Tehran also announced earlier this month that Iran's low-grade enriched uranium stockpile had exceeded the amount permitted under the nuclear deal.

Iran's expansion of nuclear activities was believed to be a response to European countries' "insufficient" measures to ensure Iran's benefit from the accord after the U.S. exit.