Under level 4 rules, gatherings are prohibited and individuals must stick to their household bubble.
However, the sports star pair threw a gathering which the registered nurse attended.
Both the Wellington Rugby Football Union and Netball New Zealand have issued statements.
"We expect our players to conduct themselves in a manner that reflects the high standards of WRFU and the Wellington Lions, and as such, we're disappointed with Kirifi's unacceptable decision-making regarding the breach," WRFU chief executive Mathew Evans said.
"We've spoken to the player in question, and he has taken full responsibility for his conduct in this incident. He knows it was unacceptable and is disappointed with himself."
Hurricanes coach Jason Holland added it was an "immature decision".
"When I heard that, it makes us pretty angry just like it makes me angry when I read anything in the paper all over New Zealand about someone breaching rules. It's been a pretty selfish and immature decision from him. He's a good man and he needs to learn from that pretty quickly," Holland said.
Kirifi also issued a statement apologising to the Wellington community.
"I want to apologise to the Wellington community, family and friends, as well as WRFU [Wellington Rugby Football Union] and Hurricanes rugby for breaching lockdown," he said.
"I take full responsibility for my actions here. I'm hugely disappointed with myself and this huge error of judgement," he said. "I know every day thousands of people are working tirelessly to stop Covid-19, so for me to break my bubble was selfish and immature."
Netball New Zealand said Reuelu-Buchanan – who was selected for the Silver Ferns Development Squad this year – has received an official warning.
"Netball NZ and the Stars management are extremely disappointed in these unacceptable actions. The matter has been dealt with and Reuelu-Buchanan has received a formal written warning," the statement said.
"I made a mistake in breaching my bubble, and I am truly sorry for letting everyone down. I have learnt from this error and I will not be making this mistake again," Reuelu-Buchanan said.