Russian Foreign Minister Sergei Lavrov has expressed fears over the threat of war in Iran after talks with his French counterpart, Bernard Kouchner.
Mr Kouchner (L) and Mr Lavrov are holding talks in Moscow
Iran's nuclear programme is topping the agenda of their meeting in Moscow.
On Sunday, Mr Kouchner raised tensions with Iran, saying: "We have to prepare for the worst, and the worst is war."
The head of the UN nuclear watchdog, Mohamed ElBaradei, has said force should only be used as a last resort to resolve the dispute.
Mr Lavrov said there was no military solution to any modern problem, including Iran's uranium-enrichment programme.
"We are worried by reports that there is serious consideration being given to military action in Iran," Mr Lavrov said.
"That is a threat to a region where there are already grave problems in Iraq and Afghanistan."
Clarifying comments he made on Sunday, Mr Kouchner said in Moscow that war was the "worst that could happen".
"Everything should be done to avoid war. We have to negotiate, negotiate, negotiate - without cease, without rebuff," he said.
Mr Lavrov and Mr Kouchner differed on the topic of a third round of UN Security Council sanctions against Iran over its uranium-enrichment programme, as well as possible unilateral sanctions imposed by the US or the EU.
Mr Kouchner urged "precise sanctions" to show that the world community was serious in its opposition to Iran's nuclear programme.
But Mr Lavrov questioned the value of unilateral moves and said the UN should not undermine a recent agreement between Tehran and the International Atomic Energy Agency (IAEA).
Russia has a UN Security Council veto over any new sanctions, and its support is seen as vital for any new approach to force Iran to end enrichment.
Iran denies it is trying to acquire nuclear weapons, and says it wants nuclear power to generate electricity for civilian use.
Tehran has warned that any new punishments could push it to stop co-operating with the IAEA.
'Lessons of Iraq'
Earlier, IAEA chief Mr ElBaradei urged Iran's critics to learn the lessons of Iraq.
He said any attack on Tehran should only go ahead after being authorised by the UN Security Council.
Iran has denied its nuclear work is intended to develop weapons
Iranian President Mahmoud Ahmadinejad has said he does not take Mr Kouchner's comments seriously.
"Media speculation is different from real words, and we do not take these remarks seriously," Mr Ahmadinejad told Iran's state news agency, IRNA.
The US has not ruled out a military attack against Iran to prevent it from acquiring a nuclear weapon.
Mr Lavrov said Russian President Vladimir Putin and French President Nicolas Sarkozy would meet in Moscow at the beginning of October. Bilateral relations between the two countries were "developing intensively", he said.