Beijing has once again lashed out at the Trump administration's decision to ratchet up sanctions on Iran's oil imports, saying that it would have ramifications for Middle East security.

"China firmly opposes the US implementation of unilateral sanctions and its so-called long-armed jurisdiction," Chinese foreign ministry spokesman Geng Shuang told reporters on Tuesday.

"The relevant move by the United States will intensify the turmoil in the Middle East and the turmoil in the international energy market."

Earlier this week, Shuang pledged that China would to its best to protect the interests of its businesses that might be targeted by the recent US decision.

On Monday, Washington announced that it would not renew its six-month waivers on sanctions, which were issued to eight major importers of Iranian oil − one of the main sources of revenues for the embattled Islamic Republic.

It came as the latest move in US efforts to reduce Iran's oil sales "to zero". Apart from trying to cut Tehran off from its main oil customers, Washington is also seeking to lock it out of the international banking system.

Earlier this month, the US designatedthe Iranian Revolutionary Guards Corps (IRGC), an elite paramilitary unit, as a foreign terrorist organisation, with Tehran responding in kind and blacklisting the Central Command.

Moreover, last year Donald Trump withdrew his country from the Obama-era nuclear deal with Tehran, under which Iran accepted restrictions on its nuclear activities in exchange for the removal of stern economic sanctions. Trump, however, echoed the claims of Israeli Prime Minister Netanyahu that the deal did not prevent Iran from pursuing the production of missiles, and stated that further pressure should be exerted on the Islamic Republic.