The tourists were beaten by three wickets in Hamilton in the opening contest in the three-match series.
The England captain told reporters: "You always are a little bit rusty when you haven't had a practice match or a training session as a side. But it was more match hardness which we were missing a little bit today. We got ourselves in position to win.
"We batted well up front, but probably loaded a little bit too much towards the end, put a bit too much pressure on our big hitters. I think both sides would have felt disappointed losing that game.
"Both sides got themselves in position to win and someone had to stand up and grab it by the scruff of the neck, and those two did it for New Zealand."
The England team included a number of players who were rested during the Twenty20 series win earlier this month.