Olonga, who left Zimbabwe in 2003 after wearing a black armband in a World Cup match to protest human rights abuses, said the situation there should be seen in the same light as apartheid was in South Africa.
"I personally believe it shouldn't go ahead simply because what is happening to people in Zimbabwe is just terrible," he said on Radio New Zealand on Tuesday.
"This is a government that has consistently abused its own people."
The New Zealand government has been pressing cricket's world body to cancel the tour amid the campaign by President Robert Mugabe's government to demolish shacks and other illegal homes and businesses, leaving at least 200,000 homeless, according to the United Nations.
The International Cricket Council (ICC) has refused to allow the tour to be cancelled and will fine the New Zealand team at least $2 million if it refuses to go.
The New Zealand government has said it will not prevent the players from going but the Green Party has invited Olongo to New Zealand to boost the campaign to cancel the tour.
He acknowledged the difficulties faced by New Zealand cricketers, and New Zealand Cricket (NZC), which faces heavy fines and financial penalties if it does not tour.
"I'm disappointed the ICC hasn't shown more compassion with regard to what's happening in Zimbabwe," he said.
"We believed that sporting sanctions made some kind of difference when South Africa was isolated.
"We believed that people who went on rebel tours were somehow crossing a line that we didn't accept ... that they were showing no concern for the people who were suffering under that oppressive regime."
Olonga said he believed it was time the world started to take notice of what was happening in Zimbabwe.
"It is immoral and the world somehow has to take a stance... possibly, probably even treat this as a situation as abnormal as apartheid."