Iran will defend itself against any military or economic aggression, Foreign Minister Javad Zarif said on Sunday, calling on European states to do more to preserve a nuclear pact with his country.
Speaking in Baghdad with Iraqi Foreign Minister Mohammed Al Hakim, Mr Zarif said Iran wanted to build balanced relations with its Arabian Gulf neighbours and had proposed a non-aggression pact with them.
"We will defend against any war efforts against Iran, whether it be an economic war or a military one, and we will face these efforts with strength," he said.
Strains have increased between Iran and the US after this month's attack on oil tankers off the UAE coast and pumping stations in Saudi Arabia.
Washington, a firm backer of Saudi Arabia, has blamed the attacks on Iran.
Tehran has distanced itself from the bombings, but the US has sent an aircraft carrier, B-52 bombers and an extra 1,500 troops to the Gulf, sparking concern over the risk of conflict.
Iraq stands with Iran and is willing to act as an intermediary between its neighbour and the US, Mr Al Hakim said.
Baghdad does not believe an "economic blockade" is fruitful, he said, referring to US sanctions.
"We are saying very clearly and honestly that we oppose the unilateral actions taken by the US," Mr Al Hakim said. "We stand with f Iran in its position."
The US and Iran are Iraq's two main allies.
Meanwhile, Iranian deputy foreign minister Abbas Araqchi arrived in Oman and discussed "regional developments" with Yousuf bin Alawi, the sultanate’s Minister of Foreign Affairs, Oman News Agency reported.
Mr Araqchi stressed the importance of peace and security in the Gulf region and rejected any direct or indirect talks with the US.
Mr bin Alawi last week said that his country was trying with other parties to calm US-Iranian tension.
Washington has been tightening sanctions against Iran as relations worsen under US President Donald Trump, who last year pulled out of a nuclear agreement signed by Iran and world powers in 2015.
In Tehran, President Hassan Rouhani floated the idea of holding a referendum over Iran's nuclear programme, which could give Iran's leaders space to manoeuvre and a chance to resolve the stand-off with the US.
Top Iranian leaders have said they are not seeking war with the US.
Mr Rouhani said that, when he was a top nuclear negotiator in 2004, he had proposed holding a referendum on the nuclear issue to supreme leader Ayatollah Ali Khamenei.
Iran has held only three referendums since its 1979 revolution -- to approve the establishment of a republic and to approve and amend the constitution.
Washington says it has built up its military presence in the region, accusing Tehran of threats to US troops and interests.
Iran has described US moves as “psychological warfare” and a “political game”.
Meanwhile, a deputy commander of Iran's elite Revolutionary Guards said the US military presence in the Middle East was at its "weakest in history", despite talk of a build-up.