Ardern rejected a suggestion not sacking her made her look weak.
"I do not accept that whatsoever. I needed to make a proportionate decision to the mistake she made, keep in mind she didn't put a meeting in her calendar. I felt the decision I made reflected the magnitude of her mistake. She made the call she would continue to be a distraction, and chose to resign."
Ardern has also come under fire for an interview with Newstalk ZB's Chris Lynch on Friday at 8am when she said she would not fire Curran.
It later it emerged Curran told Ardern the night before that she would quit - and Ardern accepted her resignation.
Ardern told Hosking when she did the interview Curran's resignation was "in the early stages" and she was not in a position to reveal a "blow-by-blow account".
"She discussed with me some of the early thinking, I am not sure she had even told her family.
"We'd love these things to be clinical and clean but they are not always, there are human elements to this, I wanted to give the minister some space and time.
Hosking questioned Ardern over an edited transcript of the interview, provided by her office to Kiwiblog's David Farrar.
Ardern said the full interview was publicly available and she had not been privy to any conversation regarding an edited transcript.