Iran's President Hassan Rouhani said US sanctions were "economic terrorism", as he sought to foster a united front from visiting regional officials on Saturday.
Addressing parliament speakers from Afghanistan, China, Pakistan, Russia and Turkey, Rouhani said they had all suffered economic pressure from the US.
"We are facing an all-out assault which is not only threatening our independence and identity but also is bent on breaking our longstanding ties," he said.
Washington has reimposed an oil embargo and other damaging sanctions on Iran since withdrawing in May from a landmark 2015 nuclear deal between Tehran and major powers.
"America's cruel and illegal sanctions against the honorable people of Iran have targeted our nation in a glaring example of terrorism," Rouhani said.
"Economic terrorism is designed to create panic in the economy of a country and fear in other countries in order to prevent investment."
The conference in Tehran was a second annual meeting of parliament speakers focused on terrorism and regional cooperation. The first was held last December in Islamabad.
Most participating countries have faced harsh sanctions and other economic pressure as part of the Trump administration's use of trade as a diplomatic weapon.
A brief truce in Trump's trade war with China was again in doubt this week after the arrest of Chinese telecom giant Huawei's chief financial officer, who was detained in Canada to face fraud charges in the US.
Washington has continued to pile fresh sanctions on Russia that began over alleged military involvement in Ukraine, while Turkey also faced penalties this year over the detention of an American pastor.
Trump has also canceled hundreds of millions of dollars in aid to Pakistan, accusing it of failing to crack down on militancy.
Sanctions affect all
Rouhani drew parallels with the sanctions and other pressure faced by the countries attending the conference.
"When they put pressure on China's trade, we are all harmed... By punishing Turkey, we are all punished. Any time they threaten Russia, we too consider our security to be endangered," Rouhani said.
"When they impose sanctions on Iran, they deprive all of us of the benefits of international trade, energy security and sustainable development. And in fact, they impose sanctions on everyone.
"We are here to say that we don't intend to tolerate such insolence."
Rouhani warned a “deluge” of drugs, refugees and attacks on Europe – which has strongly objected to the US withdrawal from the nuclear deal – if US sanctions weaken Iran’s ability to contain them.
“I warn those who impose sanctions that if Iran’s ability to fight drugs and terrorism are affected ... you will not be safe from a deluge of drugs, asylum seekers, bombs and terrorism,” Rouhani said, referring to Iran's efforts to combat smuggling, particularly from Afghanistan.
“Weakening Iran by sanctions, many will not be safe,” he said. “Those who do not believe us, it is good to look at the map.”
The European Union is working on a payment system, known as the "special purpose vehicle", to keep money flowing into Iran, but has struggled to find a host since many countries fear repercussions from the Trump administration.
Drug trafficking is a serious challenge for Iran as it borders Afghanistan – the world’s largest opium producer – and Pakistan, a major transit country for drugs.
Opium is the raw material for heroin and Afghan farmers harvest about 80 percent of the world’s supply, according to UN reports.
In 2012, Iran accounted for two-thirds of the world’s opium seizures and one-fourth of the world’s heroin and morphine seizures, a UN report published in 2014 showed.
Iran pays a heavy price to fight drug trafficking, with dozens of border guards killed in fighting drug smugglers every year. Every year, the country burns about 100 tons of seized narcotics as a symbol of its determination.
In 2013 alone, Iran spent more than $26 million to dig canals, erect walls and embankments, create new outposts and set up barbed wire along its 2,000-kilometer (1,240-mile) border with Afghanistan and Pakistan, according to government statistics.
Until 2016, Iran annually spent some $2.5 billion to fight drug trafficking, officials say.
The president said Iran has been the biggest victim of terrorism and suffered heavy human and financial damage, citing the Thursday bombing in southeastern port city of Chabahar as the latest terrorist attack which left two policemen said.
Such attacks, Rouhani said, will not deter the Iranian nation in its resolve to fight all forms of terrorism.
AFP, AP, Reuters and Press TV contributed to this story.