Club doctor Chris Hanna said Toopi had a fracture dislocation of a finger in his left hand, preventing him from grabbing objects.
"Clinton underwent surgery on Thursday to stabilise the injury and he will now be out of action for six weeks," Hanna said.
Head coach Daniel Anderson has depth within his squad to cover the loss of Toopi.
"In Vinnie Anderson and John Carlaw I have a mix of experience, size and speed, plus I also have options through other players being able to play a number of positions," Anderson said.
Toopi was disappointed with his latest setback. He did not play in the Warriors' 18-16 win over the Eels last weekend due to a hamstring injury.
"I was really looking forward to next week when we take on the Raiders in Wellington," he said.
"At least this break will give me a chance to get my hamstring right and get back to full fitness."