Iranian Revolutionary Guard officials released the short clip which it alleged showed the Type-45 destroyer being pursued by their fast attack boats.
Video shows a warship sailing in the distance while a group of smaller boats armed with machine guns follow behind at some distance.
It is unclear whether the warship in the clip is actually HMS Duncan, with one MP saying “not in a thousand years”.
HMS Duncan has been in the Strait of Hormuz for the past few weeks amid ongoing tensions between Britain and Iran.
Royal Navy vessels are now guarding all British shipping sailing through the vital waterway after the illegal seizure of the tanker Stena Impero by Iran.
Footage has previously been released of Iran confronting HMS Montrose amid tensions on the Strait of Hormuz.
“These sorts of incidents happen so regularly and have always done in the Strait, sometimes we can have two a day”
Royal Navy source
Royal Navy sources told Daily Star Online that these sorts of incidents are the “reality of operating in the Strait of Hormuz”.
They added: “These sorts of incidents happen so regularly and have always done in the Strait, sometimes we can have two a day.”
HMS Montrose is also in the Strait of Hormuz alongside HMS Duncan, and her captain Commander William King confirmed they have at least 85 run-ins with Iran.
He revealed that he believes Iran is trying to “test” Britain in the Gulf.
Speaking on BBC Radio 4, Commander King said: “I’ve had 85 interactions with Iranian forces over the last 27 days – so that gives you some idea of the intensity.
“It’s professional, it’s cordial, often there is an exchange of warnings over VHF.
“The Iranians seem to be keen to test our resolve, test our reactions, most of that time.
“We’re on guard. We’re ready to react. I’ve got 215 in my team who are highly trained and relishing the professional opportunities of being slightly under threat represents.”
Despite the regularity of the incidents however, there is still doubt whether the vessel in the Iranian video is actually HMS Duncan.
Type-45 destroyers have a distinctive silhouette due to their powerful orb-like SAMPSON tower radar – which is used to help fire the Sea Viper air defence missile system.
It appears the ship in the video – which is relatively low quality – lacks this feature.
James Heappey MP wrote on Twitter: “Not in a thousand years is that HMS Duncan.”
Mr Heappey, an aide to Prime Minister Boris Johnson, followed his tweet with the hashtag #IRGCFail.
It is unclear whether Iran may be genuinely mistaken of the warship’s identity, simply telling fibs about the vessel, or the ship actually is HMS Duncan.
HMS Duncan is one Britain’s six Type 45 destroyers alongside Dragon, Daring, Dauntless, Defender and Diamond.
The 9,400 tonne, 500ft destroyers are regarded as some of the most advanced warships in the world.
Costing over £1billion per ship, the vessels are bristling with missiles, a 4.5-inch naval gun, marines and can carry two helicopters.
It has been hailed as the world’s best air defence ship, and is the backbone of the Royal Navy.
HMS Duncan and HMS Montrose are now part of a international task force with the US and Israel to protect shipping in the Strait of Hormuz.
Five tankers and a cargo ship were attacked earlier this year, and Iran claims to have seized three oil tankers – including Stena Impero.
Iran and Britain have been at loggerheads since the Royal Marines peaceful seized Iranian flagged tanker Grace 1 as she sailed past Gibraltar.
Grace 1 is believed to have been transporting Iranian oil to the brutal regime in Syria, violating EU sanctions.
Tehran responding furiously and snatched Stena Impero, despite HMS Montrose rushing to help – being just one hour away from the tanker.
Both sides are now refusing to back down, with foreign secretary Dominic Raab refusing to negotiate with Iran.
Iran is attempting to lockdown the Strait of Hormuz in response to the axing of the so-called nuclear deal by the US.
Tensions have raged, with the US accusing Iran’s proxy forces of being behind bomb attacks on five tankers in the Gulf.
US President Donald Trump came close to launching a limited strike on Iran after the regime shot down a US drone, but backed down at the 11th hour.
Tehran has broken the binds placed on its enrichment of uranium by so-called nuclear deal with the West – but insist the measures of for power plant fuel not nuclear weapons.