Also in early April there were two separate attacks on tourists in the Bay of Island and in February visitors to Auckland tourist spots had bags stolen from buses by gun-wielding men.
Tourism New Zealand's marketing budget will swell to around $113 million following a government funding boost and this could be less effective if New Zealand's reputation is tarnished by crime, Bowler said.
"Those incidents are widely reported and in many of the cultures of our visitors from emerging markets that sort of violent behaviour and theft are very uncommon."
He said the proliferation of social media channels meant problems could be magnified in Asia where New Zealand's wider reputation was not well known.
"These incidents, while they affect one or two people, the way they're reported with social media it doesn't get reported accurately and [is] sensationalised."
He said the reaction to attacks on tourists were crucial to how the country was judged.
"Those things really matter - they count for a lot. As a community we're very good at helping victims of crime after the fact but we have to get ahead of that and reduce the number of incidents involving visitors."
While it was a complicated issue, Bowler said education about the risks to New Zealand could be good start.
Bowler said New Zealand tourism was also battling the Kiwi high dollar which meant the country was more expensive for visitors whose currency had been hit by fallout from the global financial crisis.
"There are some things in New Zealand that do seem expensive these days. Everyone's got to make a buck and we're not a high-volume low-value destination."
He made no apologies for the strength of the economy relative to other countries.
" One of our reactions to that is to focus on high-value visitors who have a higher level of discretionary income."
•New Zealand's tourist numbers are up, thanks in part to an early Easter, the England cricket team's tour of the country and marketing campaigns around the release of The Hobbit. Statistics NZ said international visitor arrivals last month were up 13 per cent on March last year, reaching 270,000, the highest ever for the month.