Act says there's a way to give workers the public holidays they want - without burdening employers with extra costs.
The party is calling for an overhaul to the current holiday laws.
It comes as cultural groups are calling for ethnic and religious communities to be able to celebrate their holidays.
The president of Universal Society of Hinduism, Rajan Zed, says the Government needs to revisit its public holiday policies as the country's demography has changed.
He said it's unfair for the Hindu community to be at work or school on their most popular festival and making it a public holiday would be "a step in the positive direction".
Zed said awareness about other religions created by such holidays like Diwali would strengthen cohesion and unity in the country.
Leader David Seymour says national holidays like Anzac Day and Waitangi Day should be mandated - but other holidays like Easter and Labour Day don't need to be.
He told Tim Dower making holidays flexible is better than creating more holidays.
"If you keep putting costs onto employment, you've got to apply some cause and effect thinking, because people who run businesses and employ people, they're going to absorb that cost."
Seymour says that the best option is to introduce some flexibility, with people able to trade out particular days.
Labour promised to make Matariki a public holiday during the election campaign.