Mike Pompeo said Islamist groups receive "far less" money from Iran for carrying out terror attacks.

US Secretary of State Michael Pompeo on Monday said that the Donald Trump administration is "not done" with Iran and will continue its pressure campaign against Tehran in a bid to force it to abandon its nuclear ambitions.

"We have implemented the strongest pressure campaign in history against the Iranian regime and we are not done. We have cut off billions in funds that Iran's leadership would have used for various nefarious purposes, not the least of which would have been their efforts to destroy Israel," he said in his address at the ''Christians United for Israel'' event.

Pompeo said that Islamist groups like Hamas and Hizballah receive "far less" blood money from Iran for carrying out terror attacks.

"It is also the case that under President Trump, the Israel haters such as Hamas and Hizballah and Islamic Jihad receive far less blood money from Iran to pursue their terrorism than ever in recent history," he remarked.

The US has said it would continue to "impose maximum pressure" against Iran till the regime gives up its "destabilising ambitions" of expanding its nuclear programme.

Attacking Iran for the persecution of minorities, Pompeo said that the practice is "intense" in the Middle East country.

"Persecution of the faithful is especially intense inside the Islamic Republic of Iran. The regime's militant adherence to the noxious tenets of the Islamic Revolution dictates all elements of life - and especially the suppression of other faiths. In Iran, if Muslims try to convert non-Muslims, the penal code calls for a death sentence," he said.

"The government does not recognise converts to Christianity. It levies beatings and solitary confinement on Christians caught worshipping in violation of government dictates," the Secretary of State added.

Pompeo underlined that the US has made efforts to protect Christians and other minorities in Iraq and several countries in the Middle East.

"This administration has made a real effort to protect Christians and other threatened religious minorities in Iraq and elsewhere, and we are making real progress. The flame of the existence of Christians must not be snuffed out. Christians'' unalienable rights in the Middle East - their right to worship must not be taken away," he said.

On Sunday, Pompeo threatened Iran with "further isolation and sanctions" after Tehran announced that it will "in a few hours" begin enriching uranium beyond the limit set in its 2015 nuclear deal with world powers.

Officials were quoted by several media reports as saying that Iran was ramping up the level of uranium enrichment beyond the 3.67 per cent permitted under the deal.

Earlier this month, Iran had increased its stockpile of low-enriched uranium beyond the cap set by the deal.

The move was a part of an Iranian effort to press Europe to salvage the accord after the US pulled out from it in May last year and reimposed punishing sanctions on Tehran, including on its oil and banking sectors.

Tehran has also threatened to abandon more nuclear commitments unless the remaining signatories of the deal -- the UK, China, Germany, France and Russia -- took steps to evade sanctions, especially to sell its crude.

The nuclear agreement was signed with an aim to limit Iran's civilian energy programme, thereby preventing it from developing nuclear weapons at some point in the future, in exchange for relief from sanctions that were crippling the country''s economy.

The US' decision of pulling out from the agreement soured its ties with Iran. In the past year, the Donald Trump administration slapped a multitude of sanctions on Tehran citing the latter's support to state-sponsored terrorism and conflicts.