China on Tuesday urged "calm and restraint" as tensions between the US and Iran escalate following US President Donald Trump's new sanctions on Iran.

"Facts have proved that these measures have had the opposite effect and aggravated regional unrest," he added.

Relations between Washington and Tehran have rapidly deteriorated over the past few weeks, after the US accused Iran of being behind a series of attacks on ships in sensitive Gulf waters -- claims hotly denied by Tehran.

On Monday, Trump further raised the stakes in an escalating regional standoff by imposing sanctions against Iran's supreme leader Ayatollah Ali Khamenei and top military chiefs.

Iran's foreign ministry spokesman denounced the sanctions as "the permanent closure of the path to diplomacy" with the Trump administration.

"We hope that the parties concerned will maintain calm and restraint and avoid further escalation of tension," Geng said.

Last week, Iran and the US teetered on the edge of military confrontation after Iran shot down a US spy drone and Trump launched a retaliatory strike, cancelling it at the last minute.

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