A travel agency says it expects bookings to Sri Lanka to drop over the next few weeks as authorities deal with the aftermath of the Easter Sunday bombings.
Sri Lanka has become an increasingly popular holiday destination and Lonely Planet named it the best country to visit for 2019.
House of Travel said about 10,000 New Zealanders visit Sri Lanka every year.
Commercial director Brent Thomas said the terrorist attacks were bound to have an impact on travel plans.
"There'll no doubt be a number of people who will come into the stores over the next few days to talk about their upcoming travels to Sri Lanka," he said.
"What we do know is obviously in these kinds of instances bookings do tail off and we're likely to see very few bookings in the next few weeks."
Mr Thomas said if there were no further attacks, he expected bookings to return to normal in about six weeks.
The Ministry of Foreign Affairs and Trade said more than 330 New Zealanders have registered as being in Sri Lanka.
SafeTravel updates Sri Lanka: Exercise increased caution. NZers in Sri Lanka - let family & friends know you are safe. Register your details on SafeTravel. If you require consular assistance contact the NZ High Commission in New Delhi on +91 1 4688 3170 or via firstname.lastname@example.org— MFATgovtNZ (@MFATgovtNZ) April 23, 2019
It was urging them to be extremely cautious at all times particularly in areas where there are large crowds.
The ministry said no-one had been affected by the bombings so far but further attacks could not be ruled out.
Meanwhile, Tara Kennaway from the tour company Intrepid said all its travellers and leaders who were currently with the group in Sri Lanka were safe and had been accounted for.
She said Intrepid had 128 staff based in its office in Colombo.
"We will be making a decision about upcoming departures and advising customers on any changes later today," Ms Kennaway said.
"In the meantime if customers wish to cancel immediately and transfer to another departure later in the year they can do so with no change fees."
Flight Centre is recommending customers to get in touch with their travel consultant who can help re-route or change itineraries as necessary.