Iran's Foreign Ministry summoned a United Arab Emirates (UAE) envoy to complain about the UAE allowing a U.S. drone, shot down on Thursday, to be launched from a U.S. military base on its territory, the Fars news agency reported on Saturday. 

Meanwhile, Iran warned the United States that any aggression against the Islamic republic would have serious consequences for U.S. interests in the region.  

"Firing one bullet towards Iran will set fire to the interests of America and its allies" in the Middle East, Iran's armed forces general staff spokesman Brigadier General Abolfazl Shekarchi told the Tasnim news agency on Saturday. 

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On the same day, Iran's semi-official news agency ISNA reported that the country has executed a "defense ministry contractor" convicted of spying for the CIA.  

"The execution sentence was carried out for Jalal Haji Zavar, a contractor for the defense ministry's aerospace organization who spied for the CIA and the American government," ISNA reported, quoting the Iranian military.  

U.S. President Donald Trump said Saturday that Washington is moving forward with additional sanctions on Iran. 

The international community has been responding to rising tensions between Washington and Tehran after Trump said on Friday that he had called off a planned military strike against Iran following the downing of the drone. 

Britain's Minister of State for the Middle East Andrew Murrison will visit Iran on Sunday for "frank and constructive" talks, the British Foreign Office said. 

"At this time of increased regional tensions and at a crucial period for the future of the nuclear deal, this visit is an opportunity for further open, frank and constructive engagement with the government of Iran," the Foreign Office said in a statement. 

Murrison, a junior minister in the Foreign Office, will call for urgent de-escalation in the region and raise concerns about "Iran's regional conduct and its threat to cease complying with the nuclear deal to which the UK remains fully committed," the statement said. 

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The Gulf of deniability

German Chancellor Angela Merkel urged the international community to seek a political solution to the issue. 

Speaking at an annual gathering of Protestant churches on Saturday, Merkel also said the Iran issue would be discussed at next week's meeting of leaders of the Group of 20 leading economies in Japan, at least at a bilateral level. 

"There has to be a political solution and that is what we are working on," she stressed. 

Russia has called on "all sides involved to show restraint," according to Dmitry Peskov, spokesman of the Russian president. 

"The situation in the Persian Gulf is very tense. We are extremely concerned about it, we're following the situation carefully and we call on all sides involved to show restraint," Peskov said on Friday. 

(With inputs from agencies)