The MoD said HMS Duncan, a type 45 frigate, is transiting to the region to ensure Britain maintains a continuous maritime security presence while HMS Montrose, a type 23 frigate, undertakes planned maintenance.
Later in the year, HMS Kent, another type 23 frigate, will deploy to the region, taking over from HMS Duncan.
It said that support ship RFA Wave Knight will deploy to the Gulf at the start of August.
"These long-planned movements do not reflect an escalation in the UK posture in the region and are routine," the MoD added.