A top Russian official Thursday dismissed criticism from the Iranian president as “emotional,” and expressed frustration over what he portrayed as Tehran’s obstinate refusal to confront suspicions over its nuclear program.

Foreign Minister Sergei Lavrov lashed back at Iranian President Mahmoud Ahmadinejad, who a day earlier described the Kremlin as a potential enemy that was overly susceptible to pressures from the international community.

" Russia has never been manipulated by anyone,” Lavrov told reporters. “It has always been guided by national interests.”

The many attempts made by various levels of Russian leadership to help Iran end the impasse are too numerous to name, Lavrov said.

“Years, not months, have been spent on that,” he said. “Iran’s response was unsatisfactory, to say the least.”

On Wednesday, Ahmadinejad accused Russian President Dmitry Medvedev of bending to U.S. pressure to pass new United Nations sanctions on Iran over its nuclear program.

“Our people are in doubt about Russia’s intentions,” Ahmadinejad said. “I hope that the Russian leaders would take into consideration our sympathy and keep the Iranian nation from counting them among its historic enemies.”

The Russian leadership was outraged by his remarks. A Kremlin aide, foreign policy advisor Sergei Prikhodko, on Wednesday accused Ahmadinejad of “political demagoguery.”

The rhetoric reflects a new depth of Moscow’s impatience with Tehran, which has long depended on Russia and China, both permanent members of the U.N. Security Council, to blunt Western pressure.

After resisting for years, the Kremlin has come around reluctantly to the notion of imposing tougher sanctions on Iran, where Russia has developed thriving trade partnerships and built a nuclear reactor.

Moscow has generally supported a nuclear fuel swap deal struck last week by Iran with Turkey and Brazil and presented as a possible way forward. The United States has dismissed the deal as a ploy to buy time and avoid sanctions. Lavrov also expressed reservations Thursday.

There was no “100% guarantee” that Tehran would uphold its obligations under the deal, Lavrov said. He pointed out that much of the recent agreement was recycled from a proposal made in 2009 by the International Atomic Energy Agency, and criticized Iran for wasting time by rejecting the earlier offer.

But it wasn’t all tough talk. The deliberate ambivalence that has long characterized Moscow’s stand on Iran was still in full view Thursday as Russian officials made a deliberate show of calling for further negotiations to help Iran sidestep sanctions.

Despite the sharp tone from the podium, Lavrov phoned his Iranian counterpart and pledged to “actively work to promote” further nuclear talks, the Foreign Ministry said.

Moscow has long maintained an essentially noncommittal position, cutting trade deals with Tehran while also accepting the courtship of the United States and Israel to join the Western camp seeking sanctions.

On Thursday, another Russian official hastened to explain that new sanctions would have no bearing on existing trade deals with Iran.

“It is most important to us that the possible sanctions that could follow the passage of this resolution should not affect the existing contracts,” Mikhail Margelov, Russian Federation Council Foreign Affairs Committee chairman, told Interfax news agency.

megan.stack@latimes.com