Eight people have been arrested as police block off streets in a bid to contain the protest at Parliament and free up Wellington streets.
Police say during today's early morning operation, human waste was thrown over some officers by protesters.
"Deliberately infecting someone with disease is a serious offence punishable by 14 years imprisonment," police said in a statement.
Attempting to infect someone also attracts a significant penalty, they said.
Meanwhile, police have confirmed officers working at the Wellington central police station have contracted Covid-19.
But they have refused to say whether personnel have been working at the large protest at Parliament.
Wellington area prevention manager Warwick McKee says with community cases rising the force is seeing a small number of positive cases of staff - including in Wellington.
He says for privacy reasons and because the situation is changing so quickly police won't confirm the number of infected staff or any other details.
The staff are isolating along with their close contacts.
Read back on all the action at Parliament here:
