The legislation passed yesterday after US Secretary of State Hillary Clinton downplayed differences with Moscow over tougher moves against Iran.
Russian Prime Minister Vladimir Putin highlighted the contrasts, saying it was "premature" to threaten sanctions against Tehran.
The new legislation protects from shareholder lawsuits those investment managers who divest funds from companies that are involved in Iran's energy sector or have provided equipment for the transport of oil or liquefied natural gas from Iran.
The bill - which passed the House 414-6 and now goes to the Senate - did not impose new sanctions, said its author, financial services committee chairman Barney Frank, a Democrat.
"What it does is to make it very clear that Americans who are deeply concerned about the prospect of Iranian nuclear power, and other aspects of Iranian governance, that they are able to act on those (concerns)," Mr Frank said.
"Several international firms continue to subsidise Iran's nuclear ambitions by investing billions of dollars in the regime's energy sector," said Republican Mark Kirk. "This legislation gives a strong 'go' signal to state and local leaders around America to get out of Iran."
Calls for tougher sanctions intensified after it was revealed that Tehran was operating a previously undisclosed uranium-enrichment facility near the holy city of Qom.
The Obama administration said it hoped to craft an international consensus on new multilateral sanctions.
But Mr Putin said yesterday that talking about sanctions against Iran could disrupt negotiations with Tehran regarding its nuclear program.
At the end of a two-day visit to Russia where Iran policy topped the agenda, Mrs Clinton said the Kremlin agreed with the US that tougher sanctions could be inevitable if Iran failed to allay the nuclear concerns.
She said she was encouraged after a meeting with Russian President Dmitry Medvedev, who first suggested last month that Russia might abandon its traditional opposition to sanctions if Iran failed to co-operate.
But Russian officials have sent mixed signals on the subject since then, leading analysts to speculate over differences within the leadership.
Mr Putin is widely viewed as the more powerful of the pair of top leaders and more sceptical about US intentions.
Asked about possible differences with Mr Medvedev on Iran, Mr Putin said yesterday: "Our President determines foreign policy. If Dmitry Anatolievich (Medvedev) said (sanctions are) inevitable, they're inevitable. But if you look closely at all his statements and the context he made them in, you'll be convinced that there's no steel-and-concrete determination towards sanctions."
Mr Putin was speaking while on a visit to Beijing, at the end of a summit of the Shanghai Co-operation Organisation, a group including Russia and China that has sought to counter Western domination of the international system.
Russia and China have frequently opposed tighter sanctions on Iran in the UN Security Council, where they hold vetoes.
Mr Putin told Chinese media the co-operation between the two countries "restrains some of our more hot-headed colleagues". He failed to identify whom he was referring to.
Mrs Clinton, who did not meet Mr Putin on her Russian visit, said: "I'm very pleased about how supportive the Russians have been in what has become a united international effort."
In an interview with ABC's Good Morning America, she added: "I believe if sanctions become necessary we will have support from Russia."
Source: The Australian