Manning is scheduled to speak at two events, in Auckland and Wellington, in early September.
The former US Army soldier was released from prison in May 2017. She had been sentenced for violating the US Espionage Act in 2013, after disclosing 1000s of classified government documents to WikiLeaks.
Due to the conviction, she requires a special direction visa to travel to New Zealand.
“Manning used a position of responsibility and authority to steal hundreds of thousands of documents that may well have put American lives at risk,” Stuff quoted National Party immigration spokesperson Michael Woodhouse as saying.
“She was convicted and sentenced and as a consequence has no good reason to be coming to New Zealand.”
Manning was banned from entering Canada last year, but secured a visa to travel there this year. Green Party MP and human rights lawyer Golriz Ghahraman, meanwhile, has insisted she poses no threat to New Zealand.
“Continuing to condemn Manning for exposing war crimes, including against children and journalists in Iraq and Afghanistan, deliberately shifts the conversation away from accountability of those responsible, effectively aligning us with the oppressor in a situation of injustice,” said Gharaman.
“National’s call to shun Manning is particularly callous, given the charges laid against her were all about speaking out against serious misuse of power and she has already served a lengthy sentence of imprisonment, at times in solitary confinement. Manning clearly poses no viable risk to New Zealand.”
Manning has never formally apologised or publicly expressed regret for leaking the documents to WikiLeaks.
“There was literally no other way I could’ve done it. I make a lot of mistakes, but that doesn’t mean I regret those mistakes, because those are learning experiences as well,” she said.