"I'm not done," he told RNZ's Morning Report.
Shaw made the announcement after failing to get the 75 percent votes of delegates at the party's online annual meeting at the weekend to be reconfirmed in the role. Co-leader Marama Davidson was reconfirmed by delegates.
After the vote Shaw had said he was "inclined" to stand again but would first seek feedback from his caucus colleagues and the wider membership. Prime Minister Jacinda Ardern confirmed he would retain his position as Climate Change Minister regardless of the leadership decision, he said.
The vote means any Green Party member can now put their name forward for the role over the next week before another vote within five weeks.
Former Green Party communications director David Cormack said the party needed to settle on a co-leader swiftly as infighting does not look good heading towards next year's election.
Political scientist Lara Greaves said although the majority of delegates backed Shaw, Auckland Central MP Chloe Swarbrick's popularity could bring a needed change for the Greens, if she decided to seek the co-leader job. Swarbrick has not said whether she will put her name forward.
