A survey of 2,000 consumers by RSM UK found that more than a quarter of people are no longer planning to take a holiday in the next 12 months.
The figure rose to 27 per cent following the escalation of the conflict involving Iran, compared to 19 per cent before the crisis intensified.
The research also found that nearly one in three consumers have already changed their travel arrangements because of the situation. Some have cancelled holidays completely, while others have postponed trips or switched destinations.
The impact appears strongest among younger travellers and families. More than half of Gen Z respondents said they had altered their plans, alongside 46 per cent of millennials and 43 per cent of families.
According to the findings, self organised overseas trips saw the biggest decline, followed by cruise holidays and adventure tours.
Concerns over safety and travel disruption were among the biggest reasons for travellers reconsidering their plans, while rising costs linked to the conflict were also highlighted.
The closure of the Strait of Hormuz has fuelled fears over global fuel supply, contributing to rising jet fuel prices and higher airfares.
Robyn Duffy said: "Rising tensions in the Middle East has forced some consumers to change or cancel travel plans this year.
"Initially thought to be a short-lived blip for international travel, the continued closure of the Strait of Hormuz has increased jet fuel prices amidst fears of scarcity, in turn pushing up airfares and squeezing demand for international travel.
"There is no doubt that consumer confidence has been rocked and that’s directly impacting travel plans for 2026.
"As a result, many consumers are opting for late bookings, deferring holidays altogether or opting for simpler, lower-risk options closer to home."
The research also suggested some holidaymakers are turning to domestic travel instead, with a small rise in interest for UK staycations, particularly among families.
Chris Tate said: "We have already seen a slowdown in London occupancy due to ongoing disruption hitting international travel plans and this trend could continue across the UK if tensions persist.
"Staycations are seeing a slight uptick in interest, particularly from families looking for certainty and value.
"However, with costs still elevated across the sector, any uplift in staycations is unlikely to fully offset the broader slowdown in travel confidence."
The findings reflect growing uncertainty across the travel industry as geopolitical tensions continue to affect booking behaviour and consumer confidence ahead of the peak summer holiday season.
