Mr Sopoaga said he'd heard of deals being made outside the negotiations.
"There are serious efforts to want to drive a wedge to divide us," he said.
"This is dangerous and we must not allow that."
Loss and damage is a major sticking point at the UN conference, with vulnerable countries pledging to dig their feet in and demand funding to repair their nations.
Australia is part of a developed nation commitment to raise climate finance to $100 billion each year by 2030 - from private and public sources.
But large developed nations don't want anything in a Paris agreement that would admit liability for compensation due to climate change.
Cook Islands Prime Minister Henry Puna said it was "no exaggeration to say this is a matter of life or death for us".
As the richest country in the region, Australia has faced calls to go in to bat for its Pacific neighbours.
Its negotiators are understood to be "strongly supporting" a vulnerable nation push to mention a goal of limiting global warming to 1.5C.