Russia warned Israel not to attack Iran over its nuclear program, saying on Wednesday that military action would have catastrophic consequences.
"Of course any possible military scenario against Iran will be catastrophic for the region and for the whole system of international relations," Deputy Foreign Minister Gennady Gatilov said.
"Therefore I hope Israel understands all these consequences ... and they should also consider the consequences of such action for themselves," Gatilov said at a news conference.
Gatilov's comments came as Iranian Supreme Leader Ayatollah Ali Khamenei said Wednesday that Tehran's nuclear course would not change regardless of international sanctions, assassinations or other pressures.
"With God's help, and without paying attention to propaganda, Iran's nuclear course should continue firmly and seriously ... Pressures, sanctions and assassinations will bear no fruit. No obstacles can stop Iran's nuclear work."
Khamenei was speaking on state television shortly after the UN nuclear watchdog declared a collapse in talks with Iran aimed at getting it to address suspicions that it is covertly seeking nuclear weapons capability.
The Islamic Republic denies this, saying its program to enrich uranium for nuclear fuel is for peaceful energy only.
But Iran's refusal to curb sensitive atomic activities with both civilian and military purposes, and its track record of secrecy and restricting UN inspections, have drawn increasingly harsh UN and separate US and European sanctions, now targeting its economically vital oil exports.
Several Iranian nuclear scientists have been killed in bombings over the past two years, attacks that Tehran has blamed on arch-adversary Israel. The Jewish state has not commented.
The United States and Israel have not ruled out resorting to military action against Iran if they conclude that diplomacy and sanctions will not stop it from developing a nuclear warhead.