Saudi Arabia's foreign minister on Monday denounced "aggressive statements" by Iran, intensifying the verbal sparring between the regional rivals after a global deal on Tehran's nuclear programme.

On Sunday, Iran's foreign ministry spokeswoman accused Saudi ally Bahrain of making "unfounded allegations" to foment "tension in the region", after the interior ministry in Manama said it had detained two men accused of trying to smuggle weapons from Iran.

"This does not represent the intentions of a country seeking good relations," Riyadh's Foreign Minister Adel al-Jubeir said of the Iranian comments.

"These statements are escalating and they are many."

Also Sunday, Iran's Foreign Minister Mohammad Javad Zarif said in Kuwait that "some countries... want conflict and war in this region".

It was a direct reference to Saudi Arabia without naming the kingdom.

Zarif dismissed as "baseless" Bahrain's claims about the weapons, calling the timing of the announcement an attempt "to prevent any progress in cooperation" with Gulf states.

Jubeir said recent comments by Iranian officials show their interference in the region and are "unacceptable to us".

He said he made the point during talks with visiting EU foreign policy chief Federica Mogherini, who briefed him on safeguards in the July 14 Vienna agreement that seeks to curb any Iranian attempt to get an atomic bomb.

- 'We understand' concerns -

It was the latest visit by a top Western official aimed at easing Saudi concerns over the deal.

On Tuesday, Mogherini flies to the Islamic republic "to start work on implementation of the agreement".

The European Union played a leading role in years of talks between Britain, China, France, Russia, the United States, Germany and Iran. US Defence Secretary Ashton Carter visited Saudi Arabia to discuss the deal last week.

Mogherini has hailed the agreement as a "sign of hope for the entire world".

It requires Iran to curb its nuclear capabilities including the number of uranium centrifuges.

International monitors will supervise the process, and in exchange an embargo that has crippled Iran's economy will be eased.

The deal would see Iran's oil exports gradually resume and billions of dollars in frozen assets unblocked.

Riyadh and its fellow Sunni-dominated neighbours accuse their Shiite regional rival of meddling in Bahrain, Iraq, Syria, Lebanon and Yemen.

Riyadh and its Gulf neighbours share with Israel a concern that Iran, made wealthier under the agreement, will be more able to support its regional proxies.

They have also worried that Iran could still be able to develop an atomic weapon -- sparking a regional nuclear race.

"We understand the concerns very well," Mogherini said.

She and Jubeir said they agreed on the need for a political solution in neighbouring Yemen.

Iran-backed Huthi rebels, aided by forces loyal to former president Ali Abdullah Saleh, advanced from their traditional northern stronghold in Yemen last year.

They seized territory and moved on the southern city of Aden where internationally supported President Abedrabbo Mansour Hadi took refuge.

He fled to Saudi Arabia, which assembled an Arab coalition that began bombing the Huthis in late March.

Anti-rebel fighters on the ground last week regained control of much of Aden.

The coalition unilaterally announced a five-day truce that began at midnight (Sunday 2100 GMT) so aid can reach a country facing what the United Nations has described as an "unfolding humanitarian catastrophe".