Going into the three-match series with thoughts of second spot in the world one-day rankings on their mind, the Black Caps were brought back down to earth with a thuoughts as they suffered their first ever one-day loss to the home side.
Vettori admitted his team were now focused on ensuring the series did not escape their grasp as they look to bounce back in the second match at the Shere Bangla National Stadium on Saturday.
"We have to win the next game, that's the most important thing, to keep ourselves alive in the series. Hopefully we've learned a lot from this wicket and have got some game-time under our belts," he said.
"We're hoping to come back a better side in the second game."
New Zealand were on the back foot the moment Bangladesh captain Mohammad Ashraful won the toss and decided to bowl in damp and overcast conditions.
Mashrafe Mortaza was the chief destroyer as the Black Caps top order crumbled to 79 for six. Mortaza eventually finished with figures of four for 44.
Jacob Oram (57) and captain Daniel Vettori (30) steadied the ship with a 70-run stand but it wasn't enough as the Black Caps limped to 201 for nine, their lowest total against Bangladesh in 12 meetings.
A man-of-the-match display from opener Zunaed Siddique, who scored a career-best 85, and a half-century from captain Mohammad Ashraful capped off a good all-round performance and deserved win for Bangladesh, who were without the services of 14 front-line players following their defection to the unsanctioned ICL.
Vettori refused to blame the performance on a lack of cricket for his players, who have been out of action since July following the postponement of the Champions Trophy.
"We are a little bit underdone but I don't think that should take anything away from the way Bangladesh played today. They made the most of the conditions," he told Sky Sports.
"To have us 65 for five, they really put us under the pump and we managed to recover a little bit - Jacob Oram played really well - but in the end 200 on a good deck wasn't enough."
Ashraful, on the other hand, was understandably delighted by the victory.
"I am happy we played as a unit," Ashraful said.
"I am elated that it's the first win against New Zealand and first against a major country under my captaincy.