Police Minister Fikile Mbalula said the robbery undermined South Africa as a tourism destination.
He told ambassador Gerards: "We don't have words to express our embarrassment and our regret for what happened to the people of the Netherlands."
Mbalula met the Dutch tourists on Tuesday afternoon.
Police spokesman Brigadier Vishnu Naidoo said no arrests had been made.
The Southern Africa Tourism Services Association expressed concern that the attack would harm the industry.
"It is not good for our image," Satsa's CEO David Frost said. "Exactly what impact it will have [on tourism] we don't know. It is clearly not going to have a positive impact.
"What was good is that there was a very co-ordinated response from South African Tourism, and many of Satsa members, to sort the issue out as quickly as we could.
"When an incident like this occurs we have to use it as a learning opportunity," said Frost. "The important thing is that we all need to sit down with the minister and his top team to sort out pre-emptive measures and operating procedures that will prevent these things from happening again."
According to Stats SA, the Netherlands ranked ninth on the list of countries of tourists visiting South Africa in mid-2017.
Stats SA will release its new figures on Thursday.
- Additional reporting by Penwell Dlamini
Nightmare holiday: Dutch tourists robbed and terrorised
Tourism and crime: Dutch tourists held up at gunpoint, robbed and terrorised in bus from airport
Forty-nine hours after a group of Dutch tourists set foot in South Africa for a fun three-week holiday they returned battered and bruised to their home country after becoming the victims of yet another airport robbery.
"We are safe now but we are in shock and want to go back. We just landed for a 22-day trip but the fun has gone," one of the passengers, Peter Bakker, told the Dutch newspaper Telegraaf.
The group of 36 tourists, most of them over 60, were scheduled to leave South Africa on a flight on Tuesday night and arrive back in Amsterdam around 10.30am on Wednesday - spending not even 50 hours in this country.
The tourists, who arrived in South Africa on Sunday night, were robbed on their way from OR Tambo International Airport to their accommodation in Fourways.
Their bus, they said, was stopped by a vehicle with police markings. One man was dressed in a police uniform, the other five in civilian clothing.
Describing the experience as "hell", Bakker said the hands and feet of the bus driver and the tour leader were bound with cable ties. Five men boarded the bus and stole whatever they could.
"People panicked, and firearms were aimed at them. In two cases, the trigger was pulled but the gun didn't fire," said Bakker.
Several of the tourists were assaulted.
"The suitcases were taken out of the cargo area. They were busy for 20 minutes. People cried and are in shock. They took the keys from the bus and disappeared."
Spokesman for Dutch travel company ANWB, Ad Vonk, said the tourists lost their phones, bags and luggage.
"A lot of things are gone."
The Dutch ambassador to South Africa, Marisa Gerards, said the tourists had booked an organised trip instead of striking out on their own because they had safety worries.
"It was [ironic] that those who were so concerned about their safety were so brutally robbed."
After the robbers left, passengers freed themselves. The driver had a spare key in the cargo area and drove the tourists to their hotel.
Vonk said most of the tourists were 60 or older, but there were a few women in their late 20s and early 30s.
Some of the passengers were treated for light injuries.
The passports of three passengers were stolen. They were issued with new passports before flying back to the Netherlands.
Vonk said some Dutch tourists had been victims of crime in South Africa before but there had been "nothing on this scale".
He said his company was not reconsidering organising tours to South Africa "because it is a beautiful country" and is popular with Dutch tourists.
The tourists' 22-day travel programme cost them about R35,000 (€2200) each.
The tour programme included visiting Johannesburg, Pretoria, Cape Town, Swaziland, Lesotho, the Wild Coast, the Kruger National Park, the Drakensberg, Route 62 and the Garden Route.
Police Minister Fikile Mbalula said the robbery undermined South Africa as a tourism destination.
He told ambassador Gerards: "We don't have words to express our embarrassment and our regret for what happened to the people of the Netherlands."
Mbalula met the Dutch tourists on Tuesday afternoon.
Police spokesman Brigadier Vishnu Naidoo said no arrests had been made.
The Southern Africa Tourism Services Association expressed concern that the attack would harm the industry.
"It is not good for our image," Satsa's CEO David Frost said. "Exactly what impact it will have [on tourism] we don't know. It is clearly not going to have a positive impact.
"What was good is that there was a very co-ordinated response from South African Tourism, and many of Satsa members, to sort the issue out as quickly as we could.
"When an incident like this occurs we have to use it as a learning opportunity," said Frost. "The important thing is that we all need to sit down with the minister and his top team to sort out pre-emptive measures and operating procedures that will prevent these things from happening again."
According to Stats SA, the Netherlands ranked ninth on the list of countries of tourists visiting South Africa in mid-2017.
Stats SA will release its new figures on Thursday.
- Additional reporting by Penwell Dlamini