The two sides reached agreement last week on a schedule to finish building the plant after years of delays.
Some Western countries fear Iran is trying to build nuclear weapons but Tehran says its programme is peaceful.
The UN Security Council has already imposed two sets of sanctions on Iran for refusing to stop enriching uranium.
Iranian assurances
Enriched uranium is used as fuel in nuclear power stations. When it is more highly enriched, it can be used to make nuclear weapons.
There are two pressurised water reactors at the Bushehr site, one of which is reportedly near completion and likely to be the first major Iranian reactor to go on stream.
Russian officials have previously said the plant could be operational within six months of fuel being made available.
Iran first planned a reactor near the south-western port of Bushehr with German assistance in 1974.
Those plans were abandoned after the Islamist revolution in 1979 but the Russians picked up the project in 1992.
The Russian company building the plant, Atomstroiexport, said the containers of fuel had been inspected and sealed before delivery by the UN’s nuclear watchdog, the International Atomic Energy Agency.
Russia’s foreign ministry said it had received assurances from Tehran that the fuel would not be used anywhere but at Bushehr.
The foreign ministry statement urged Iran to stop enriching uranium, saying there was no longer any need.
But a senior Iranian official said his country would not halt uranium enrichment under any circumstances, Reuters news agency said.
