The Australian Greens have resolved to vote against any legislation enabling a plebiscite on marriage equality.

"No matter what the enabling legislation for a plebiscite looks like, the Greens will vote against it. We should never put questions of human rights to an opinion poll," said Greens Leader Richard Di Natale.

"The easiest, simplest, quickest, most effective, least costly and least harmful way of ensuring equality in marriage is through a vote in the parliament, and we can do that next week should the Prime Minister decide to show some leadership.