"The Russian side confirmed its readiness to contribute to the promotion of this dialogue with the goal of reaching a fair agreement based on the principles of international law," the Kremlin said in a readout of a call between the leaders.

The latest round of the talks between Tehran and Washington, initially set for May 3, was postponed, with mediator Oman citing "logistical reasons" for the delay.

The two countries have held three rounds since April 12, their highest-level contact since the United States withdrew from a landmark deal with Iran in 2018, during Donald Trump's first term as president.

Russia has deepened its military and diplomatic ties with Iran since it launched its offensive on Ukraine in February 2022.

The two countries, both under massive Western sanctions, signed a strategic partnership earlier this year. Most recently, Moscow has sent two planes to help put down a fire after a deadly explosion in Iran's biggest commercial port.

Russia earlier confirmed its readiness to help find a diplomatic solution to the stand-off between Washington and Tehran, and to play any role in the talks.