Iranian President Hassan Rouhani has cautioned US President Donald Trump about pursuing hostile policies against Tehran, saying "America should know … war with Iran is the mother of all wars," the state new agency IRNA reports.

Key points: Hassan Rouhani's comments seem to address reported efforts by Washington to destabilise Iran's Islamic government

Hassan Rouhani's comments seem to address reported efforts by Washington to destabilise Iran's Islamic government US State Department has shared anti-Tehran posts online in past month

US State Department has shared anti-Tehran posts online in past month Secretary of State Mike Pompeo is scheduled to give 'Supporting Iranian Voices' speech on Sunday (local time)

Iran faces increased US pressure and looming sanctions after Mr Trump's decision to withdraw the United States from a 2015 international deal over Iran's nuclear program.

Addressing a gathering of Iranian diplomats, Mr Rouhani said:

"Mr Trump, don't play with the lion's tail, this would only lead to regret," Mr Roiuhani said, according to IRNA.

"America should know that peace with Iran is the mother of all peace, and war with Iran is the mother of all wars."

"You are not in a position to incite the Iranian nation against Iran's security and interests," Mr Rouhani added, in an apparent reference to reported efforts by Washington to destabilise Iran's Islamic government.

Earlier in Washington, US officials familiar with the matter told Reuters that the Trump administration has launched an offensive of speeches and online communications meant to foment unrest and help pressure Iran to end its nuclear program and its support of militant groups.

Current and former US officials said the campaign paints Iranian leaders in a harsh light, at times using information that is exaggerated or contradicts other official pronouncements, including comments by previous administrations.

The White House declined comment on the campaign. The State Department also declined to comment on the campaign specifically, including on Secretary of State Mike Pompeo's role.

US State Department has spread anti-Tehran posts online

A review of the State Department's Farsi-language Twitter account and its ShareAmerica website — which describes itself as a platform to spark debate on democracy and other issues — shows a number of posts critical of Tehran over the last month.

Iran is the subject of four of the top five items on the website's "Countering Violent Extremism" section.

They include headlines such as "This Iranian airline helps spread violence and terror".

In social media posts and speeches, Mr Pompeo also appeals directly to Iranians, the Iranian diaspora and a global audience.

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On June 21, Mr Pompeo tweeted out graphics headlined: "Protests in Iran are growing," "Iranian people deserve respect for their human rights," and "Iran's revolutionary guard gets rich while Iranian families struggle."

The tweets were translated into Farsi and posted on the ShareAmerica website.

On Sunday (local time), Mr Pompeo will give a speech titled "Supporting Iranian Voices" in California and meet Iranian Americans, many of whom fled the Islamic Revolution that toppled Shah Mohammad Reza Pahlavi.

"Let me be clear, we are not seeking regime change. We are seeking changes in the Iranian government's behaviour," a State Department official said in response to questions from Reuters.

"We know we are driving Iran to make some hard choices. Either they can change their ways or find it increasingly difficult to engage in their malign activities," said the official, speaking on condition of anonymity.

"And we believe we are offering a very positive vision for what we could achieve and what the Iranian people could have."

Washington has long called Iran the world's leading "state sponsor of terrorism" because Tehran arms and funds proxy militant groups like Lebanese Hezbollah.

In May, Mr Pompeo flagged strong sanctions on Tehran to ensure "Iran has no possible path to a nuclear weapon, ever."

Iranian leaders urge the destruction of the US and Israel, and Iranian proxies have killed hundreds of US soldiers and diplomats since the Islamic Revolution.

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Reuters