Simon Bridges says he's learned his lesson and won't be talking about Jami-Lee Ross' health issues anymore.
Mr Ross, the MP for Botany, is taking leave from Parliament for unspecified "personal health issues".
The National Party leader was widely criticised last week after describing Mr Ross' condition as "perhaps actually embarrassing. A lot embarrassing, potentially".
Appearing on The AM Show on Monday, Mr Bridges said he's already expressed regret for his "poor choice of words" and is now "moving on".
"I'm doing the right thing which is drawing a line under it, respecting his privacy, and I'd ask media to do that as well," he told host Duncan Garner.
"I've learned my lesson. I'm not going to talk about things that ultimately are around privacy. I'm not going to talk about those things... These are health matter for him, and I'm not going to be talking about my conversations with him. I'm drawing a line under this. I'm not talking about them."
Mr Bridges said despite the intrigue around Mr Ross' departure and the long-running expenses leak investigation, he's "resolutely focused on things that matter to New Zealanders".
"I consistently try and talk about these things that matter to New Zealanders because I know this other stuff isn't part of their lives.
"As they get up right now and they're getting ready for work and they're going for work, it's the petrol prices that are really hurting them - $200 more in tax they're paying. The rest is stuff that in politics comes along and you've got to deal with, and we all know that is true.
"But what is also true is National's focus on what matters to New Zealanders, and it's the stuff that you know, I'm consistently trying... to be talking to you and viewers about."
Mr Ross was reportedly "pissed off" at Mr Bridges' comments. It's not clear when he'll be back in Parliament.
Mr Bridges said if National forms the next Government, they will repeal the regional fuel tax that added 11.5c a litre to prices in the Auckland region, but wouldn't roll back any others - including those applied by the previous National Government.
"What we did is nowhere near comparable to this. We didn't go as fast or as hard as radical as this Government did, and we didn't do it when petrol prices were already rising radically."