Brenton Tarrant, 28, accused of carrying out attacks on two mosques in Christchurch on Friday that resulted in the deaths of at least 50 people, including children, appeared in court on Saturday charged with murder.
The prime minister's office verified that it received the manifesto.
He added that the country was proud of Naeem Rashid, one of the victims, who the premier said would be recognised for his courage with a national award.
He has so far been charged with one count of murder, although judge Paul Kellar said it's "reasonable to assume" that more charges will follow, after yesterday's deadly shooting.
"I can tell you one thing right now, our gun laws will change", Ardern told reporters on Saturday, saying a ban on semi-automatic weapons would be considered.
He added, two other people arrested near to where the massacres happened are not believed to be involved in the attacks.
The mosque attacks have shaken this usually peaceful country, which prides itself on welcoming refugees fleeing violence or persecution.
Twelve operating theatres worked through the night on the more than 40 people wounded, said hospital authorities.
NZ mosque shootings toll rises to 50, authorities to begin releasing bodies
New Zealand has in the past tried to tighten firearm laws, but a strong gun lobby and culture of hunting has stymied such efforts. They included Asif Shaikh, 44, who said he was among more than 100 people at the Al Noor mosque when the attacker came in.
Furthermore, a circular was released by the foreign ministry notifying details regarding visa facilitation for the immediate family members of the Pakistani victims.
She said neither the gunmen nor the suspected accomplices were on any terrorist watchlist in New Zealand or Australia.
Her stance was welcomed by New Zealand Police Commissioner Mike Bush.
New Zealand has in the past tried to tighten firearm laws, but a strong gun lobby and culture of hunting has stymied such efforts.
Police warned Muslims all over the country not to visit mosques "anywhere in New Zealand" in the wake of the Christchurch attacks.
In Sydney, a silver fern - the symbol of New Zealand - was projected onto the side of the world famous Opera House.
"Unfortunately, we are all too familiar with the devastating effect a mass shooting has on a faith community", said Meryl Ainsman, chair of the board of the Jewish Federation of Greater Pittsburgh.
Once identification is complete the names will be made public, Bush said. "We are filled with grief over this senseless act of hate".
"Lilik has been a valued part of our engineering team in Christchurch for 16 years, but he first got to know the team even earlier when he worked with our aircraft engineers in a previous role overseas", Air New Zealand Chief Executive Christopher Luxon said in a statement. "My message was sympathy and love for all Muslim communities", she said she told him.