The request was rejected by President Vladimir Putin on concerns that S-400 missile sale to Tehran may stoke further tensions in the Middle East, Bloomberg said in a report.
Russia has rejected an Iranian request to buy S-400 missile defence systems, a Bloomberg report said on Thursday quoting an unnamed senior Russian official.
The official said the request was rebuffed by Russian President Vladimir Putin on concerns that the sale would stoke more tension in the Middle East.
The report came as emergency summits of Arab leaders are being held in the Saudi city of Mecca on Thursday to discuss drone strikes on oil installations in Saudi Arabia and attacks on four vessels, including two Saudi oil tankers, off the UAE coast earlier this month.
Tehran has denied involvement in either attack.
The US is pursuing what it calls a "maximum pressure campaign" of sanctions against Iran to reduce its revenue streams from oil and other economic activities, in an attempt to curb what it sees as Tehran’s disruptive policies in the region.
The Bloomberg report said Russia’s reaction to Iran’s request reflects the delicate balance of power in the Persian Gulf, where a showdown is brewing between the Islamic Republic on one hand, and the US and its Gulf Arab allies on the other.
On Wednesday, US National Security Advisor John Bolton said that the attack near a UAE bunkering hub was connected to the strike on pumping stations on the kingdom’s East-West pipeline — both alternative oil shipping routes to the Strait of Hormuz — and a rocket attack on Baghdad’s Green Zone.
"There is no doubt in anybody’s mind in Washington who is responsible for this and I think it’s important that the leadership in Iran know that we know," Bolton said.
He said the United States was trying to take a "prudent and responsible" approach but warned Tehran against any new attacks.
Earlier this month, US President Donald Trump approved deployment of additional 1,500 troops in the region.