The right-handed Guptill hit 10 fours and three sixes in his 48-ball 80, sharing an opening stand of 62 with captain Kane Williamson, after an unchanged New Zealand won the toss on a green-tinged surface at Mohali to post 180-5.
Sharjeel Khan (47) gave his team a brisk start in their chase with New Zealand either bowling too short or too full on his pads as Pakistan raced to 61-0 in five overs.
However, the rest of Pakistan’s batsmen found it hard to hit the boundaries after paceman Adam Milne dismissed the left-handed opener, who struck nine fours and a six in his 25-ball knock.
Pakistan captain Shahid Afridi, who will retire from international cricket after the tournament, promoted himself to number five in a bid to provide momentum but his vigil at the crease lasted nine balls in which he scored 19.
It was New Zealand's third straight win in Group Two after victories over hosts India and local rivals Australia.
Pakistan, who are in second place with one win from three matches, need to beat the Australians in their final game and hope other results go their way to reach the last four.
Third-placed Australia and India in fourth each have one win from two matches, while bottom side Bangladesh, who came through the qualifiers to join the Super 10 stage, have little chance of progressing after losing their first two games.
