Type 23 frigate HMS Kent will set sail in September (Picture: MOD).
Britain is to send two more ships to the Gulf.
Type 23 frigate HMS Kent will sail to the region later in the summer and will be supported by Royal Auxilliary support ship RFA Wave Knight.
The Ministry of Defence (MOD) said HMS Kent will replace Type 45 Destroyer HMS Duncan as it undergoes "routine maintenance".
The MOD stressed the deployments are not in response to increased tensions with Iran.
In a statement, a spokesperson said: "We regret the information regarding the pre-planned deployment of RFA Wave Knight has been conflated with the deployment of HMS Kent to the Gulf.
"We remain focussed on ensuring de-escalation in the region and will act appropriately to protect UK interests and ensure Freedom of Navigation. The deployment of HMS Kent to the Gulf later this year, to ensure we have a ship at sea, reflects just that."
Last week, it was announced that HMS Duncan was being sent to the region while HMS Montrose "comes off task for pre-planned maintenance".
HMS Montrose is already permanently deployed to the Gulf.
The news comes less than a day after the two candidates to be Britain's next prime minister said they would not back the US in a war against Iran.
Relations between Iran and the West have been strained since President Donald Trump pulled the US out of the 2015 Iran nuclear deal.
The UK has a long-standing maritime presence in the Gulf and the Indian Ocean.
Since 1980, units of both the Royal Navy and the Royal Fleet Auxiliary (RFA) have maintained a constant presence in the region.
There are currently 1,200 UK personnel deployed on Operation Kipion, the operational name for British forces in the Gulf and the Indian Ocean.