Trump pulled the United States out of the multinational deal under which sanctions on Iran were lifted in return for curbs on its nuclear programme verified by the International Atomic Energy Agency (IAEA).
But Washington has also warned European allies that they face possible penalties if they violate USA sanctions, which Washington says are aimed at reducing Iranian oil exports to "zero" - a level that would deprive Iran's economy of its principal source of revenue and economic growth.
Since Trump's shock move in May, which dismayed all other signatories, Washington has warned other countries to end trade and investment in Iran and stop buying its oil from early November or face punitive measures.
Mohammad Ali Jafari, who commands the Islamic Revolutionary Guard Corps, Iran's most powerful military force, responded on Thursday.
Rouhani expressed hope, however, that the diplomats would be able to make progress.
Referring to the firm stands adopted by Iran's president against recent USA ill-wishing strategies and imposition of new oil sanctions against Iran, General Jaafari expressed hope that people from all walks of life along with the country's officials to adopt a unified stance to achieve their goal. "We will make the enemy understand that either all can use the Strait of Hormuz or no one".
Iran's Islamic Revolution Guards Corps (IRGC) warned Thursday that it could block the Hormuz Strait in the Gulf should the US prevents its oil exports, semi-official ISNA news agency reported.More news: Insane brawl breaks out in FIBA qualifier between Australia and Philippines
More news: Things to know about abortion and the Supreme Court
More news: How Japan cleaned up at the World Cup
With a third of the world's sea-borne oil passing through it every day, the Strait of Hormuz is a strategic artery linking Middle East crude producers to key markets in Asia Pacific, Europe, North America and beyond.
The announcement of the arrests coincided with the start of a European tour by Iran's President Hassan Rouhani that began on Tuesday and included visits to Switzerland and Austria. "To save the deal, other signatories should compensate for USA sanctions", a senior Iranian official told Reuters on Friday.
Tehran will continue cooperation with Europe if the remaining parties to the accord can meet Tehran's expectations during the meeting of the foreign ministers, Rouhani said, according to Press TV.
The EU, once Iran's biggest oil importer, has vowed to keep the 2015 nuclear deal alive without the United States by trying to keep oil and investment flowing.
He said that up to now, the package of incentives proposed to Iran were "disappointing", and that they "lacked an operational solution and a specific method for cooperation, and featured just a set of general commitments".
The US unilaterally withdrew from the Iranian nuclear deal in May.
Mogherini noted that companies pursuing business in Iran "have been acting in good faith based on the commitments contained in the JCPOA and endorsed at the highest level by the UN Security Council" and said the treaty states were committed to providing "clear and effective support for economic operators trading with Iran".