In an open letter to UK trade partners, Verhounig attempted to provide agents with reassurance after weeks of questions from customers around pricing.
The US and Israel launched wide-ranging strikes on Iran, killing the country's supreme leader on 28 February, just over a month ago.
The crisis has not only severely impacted travel across the Middle East but also created higher-than-normal demand in other popular destinations such as the western Mediterranean.
Verhounig said prices for land holidays to Spain and Portugal have increased by up to 15% in recent weeks.
He said: "Quite simply, the lates market is dying. The era of short booking windows is drawing to a close and the lates market with it.
"The escalating crisis in the Middle East should end any lingering illusion that the travel industry can rely on short booking windows, last-minute demand and price slashing.
"Geopolitical shocks are no longer rare disruptions; they are becoming a defining feature of the global economy and consumer behaviour is adjusting fast."
He added: "Persistent geopolitical volatility will force both operators and travellers to plan further ahead, without the fallback of distressed inventory suddenly appearing to boost suppliers’ coffers and tempt consumers with a perceived bargain."
'No plans to introduce fuel surcharge'
Verhounig ruled out Ambassador increasing prices in the short term, saying: "Ambassador is well positioned from a fuel and cost perspective.
"Our 2026 and 2027 programmes are fully hedged and there are currently no plans to introduce any fuel surcharge."
Consumers, he added, are "not naive". "They understand that geopolitical instability, fuel price swings and wider economic pressures can quickly translate into higher fares and reduced availability, not just in peak periods but throughout the year," he continued.
Verhounig thanked trade partners for their support before highlighting how land-based holidays are already beginning to "rise in price as a result of recent geopolitical disruption".
He added: "There has never been a better opportunity to promote the advantages of Ambassador’s no-fly sailings to your customers."
Demand for Ambassador's 2026 itineraries is "exceptionally strong", Verhounig said, with more than 87% of capacity selling out across the programme.
On 12 March, Ambassador launched its 2028/29 season, with sales in the first hour alone amounting to over a third of the total the line achieved across one day when launching its 2027/28 season last June.
