Iran has dismissed a sanctions bill approved by the US House of Representatives that toughens existing measures imposed on Tehran over its disputed nuclear programme.

Despite fears the new legislation could thwart hopes for a diplomatic breakthrough in the wake of Hassan Rouhani's election victory, the lower house of the US Congress overwhelmingly passed the sanctions to further limit the Islamic republic's access to the global market for its oil exports and punish rebellious customers who continue to buy Iranian crude.

"We have no doubts that sanctions is a failed policy," said Iran's foreign ministry spokesman, Abbas Araqchi, according to quotes published by the website of the state-run broadcaster IRIB.

"Sanctions and intensifying them … will only make the nuclear issue more complex and more difficult to resolve," he added.

Critics of the bill said tougher sanctions could not have come at a worse time given that Rouhani will be inaugurated on Sunday and has not yet had the chance to compromise. But those who supported the legislation said the new Iranian president would have little say with regards to Tehran's nuclear policy, which is in the hands of the supreme leader, Ayatollah Ali Khamenei.

Tehran's nuclear trajectory has experienced considerable shifts during previous administrations in Tehran. Under the reformists in 2003, when Rouhani was the chief nuclear negotiator, Iran for the first time agreed to halt its enrichment of uranium and allow more scrutiny of its facilities by international inspectors.

The bill will have to be voted on by the US Senate in September after summer recess and signed by Barack Obama before it comes into effect.

John Boehner, the Republican speaker of the house, and Nancy Pelosi, the Democratic leader, both spoke in favour of the measure, which was passed by 400 votes to 20. Boehner told representatives that Iran was a "global menace", and Pelosi said sanctions should be kept in place because they had had an impact.

Some analysts fear the bill might play into the hands of hardliners in Tehran who say negotiations with the west are futile. Rouhani won the presidential election in June on promises of moderation and improved relations with the international community.

The bill also highlights a rift between the White House and Congress over the US's Iran policy. The Obama administration, which does not appear to believe Iran's leaders have decided to make a nuclear bomb just yet, says it is willing to continue negotiations and recently sent a positive signal to Tehran by easing restrictions on medicine and medical devices.

Rouhani is expected to name Mohammad Javad Zarif as Iran's new foreign minister, in a move seen as Tehran's olive branch to Washington.

Russia said the new bill would not help the nuclear negotiations. "Any additional sanctions are actually aimed at the economic strangulation of Iran, but not at solving the problem of non-proliferation," its deputy foreign minister, Gennady Gatilov, told Russia's Interfax news agency. "What has been done through the security council is quite adequate and sufficient."

Jim McDermott, a Democrat representative for Washington state who spoke against the bill, said it would undermine efforts to resolve the nuclear dispute with Iran. "It's a dangerous sign to send and it limits our ability to find a diplomatic solution to nuclear arms in Iran," he said.

Jamal Abdi, policy director at the National Iranian American Council, echoed McDermott, saying: "The Iranian people sent a clear message in recent elections that they support moderation over radicalism, but that message has fallen on deaf ears among House leadership.

"By forcing this vote before the US has an opportunity to engage with Iran's incoming government, the House risks squandering a major opportunity and only makes a nuclear deal more difficult to achieve."