Prime Minister Jacinda Ardern has returned from the Christmas break saying she is refreshed and optimistic her government is on track to achieve its ambitious goals in housing, health and poverty.

Her coalition team set "a pretty big agenda" to achieve within its initial 100 days in power and in her first media appearance of the year Ardern denied she would be backtracking anytime soon or claiming her plans were too ambitious.

"You cannot in your first year (in government) be defeatist and lack that kind of ambition," she said.

Instead, she said her team had made important starts on these "long-run issues".

To ensure they made continual progress, her ministers had identified smaller goals along the way, she said.

In the case of boosting Auckland and the country's housing supply, she said an early sign government policies were working would be evidence homelessness had reduced.

"I'm realistic that eradicating homelessness in one term would be very difficult, but I'm not going to sit back and say it's impossible," she said.

Ardern also rebuked United State President Donald Trump for using "offensive language" to dismiss an immigration bill, when he said why should America take in more people from Haiti and countries in Africa.

She asked how Kiwis would feel if New Zealand was described that way.

"There's no other way to describe a response to that (comment) other than just it's hugely offensive," she said.