US Secretary of State Mike Pompeo on Tuesday said his country did not want war with Iran, despite sending nuclear-capable bombers to the region.
Mr Pompeo's comments came during his first official visit to Russia, a key backer of Tehran, which has blamed the current crisis on Washington's decision to pull out of the Iran nuclear deal.
"We fundamentally do not seek a war with Iran," he said, standing alongside Russian Foreign Minister Sergey Lavrov after talks in Sochi.
"We have also made clear to the Iranians that if American interests are attacked, we will most certainly respond in an appropriate fashion.
"We are looking for Iran to behave like a normal country."
Mr Pompeo referred to Tehran's backing of the Houthi rebels in Yemen, who are "launching missiles into areas where there are Russians and Americans travelling.
"These missiles could easily kill a Russian or an American," he said.
Mr Lavrov said Moscow would work "to ensure this situation does not descend into a military scenario".
"I hope that reason will triumph," he said.
He said he hoped that reports in the US media that President Donald Trump was planning to send 120,000 troops to counter Iran were wrong.
The president rejected The New York Times report, saying it was "fake news", but did not rule out sending "a hell of a lot more" soldiers in the future.
Mr Pompeo was set to meet Russian President Vladimir Putin at his residence in Sochi later in the evening, for the countries' highest-level talks in nearly a year.
Mr Putin's spokesman Dmitry Peskov earlier on Tuesday criticised what he called Washington's "maximum pressure" campaign on Iran, saying it would only drive Tehran into a corner.
Mr Pompeo cancelled a stop in Moscow on Monday for an unscheduled meeting in Brussels with European foreign ministers, who have been uncomfortable with the US direction on Iran.
Washington last year pulled out of a nuclear deal backed by Europe, Russia and China, which curbed Iran's nuclear ambitions in return for sanctions relief.
It has since reimposed sweeping sanctions on Iran to reduce Tehran's regional influence.
The US has recently increased the pressure, sending an aircraft carrier strike group and nuclear-capable B-52 bombers to counter what it said were threats from Iran.
UN inspectors have said Iran is complying with the deal, and Moscow last week denounced new US sanctions on the country's mining industry, calling for talks to save the nuclear accord.
Before the Sochi talks, Mr Pompeo and Mr Lavrov said they wanted to see ties between the US and Russia improve. But the pair had little to agree on about three hours later.
Mr Pompeo warned Russia not to meddle in the US presidential election next year, calling on Moscow "to demonstrate that these types of activities are a thing of the past".
Mr Lavrov repeated Moscow's denial of interference and said it was "absolute fiction" that Russia had colluded with the Trump campaign.
The report by US special counsel Robert Mueller found that Russia interfered in the 2016 US election but did not conclude that the Trump campaign colluded with Moscow.
Mr Pompeo also said he had urged Mr Lavrov to end Russia's support for Venezuelan President Nicolas Maduro.
But Mr Lavrov flatly rejected the request, denouncing US and opposition "threats" against the Maduro government.
The talks also touched on arms control and the conflict in Syria, in which Russia and the US back opposing sides.
The US administration has kept up a campaign of pressure, including sanctions on Russia over the election meddling and Moscow's support for armed separatists in Ukraine.