Forest and Bird says ramped-up protests against 1080 across the country are out of line.
The Department of Conservation (DoC) has involved police after several incidents of vehicle tampering - believed to be in relation to 1080 protests.
Wheel nuts were allegedly loosened on staff vehicles in two regions, and a wheel came off a car while a contractor was driving. 1080 baits have also been left in a letterbox at a DOC address.
Forest and Bird chief executive and former Green MP Kevin Hague says 1080 isn't his preferred method, but it is effective.
"1080 use is extremely important and useful for protecting the ecology that is so precious to us," he said.
Mr Hague says strong-arming DoC workers isn't the way to go.
"Forest and Bird is appalled by the reported behaviour of loosening wheel nuts and that kind of thing that places people's lives at risk. That's just intolerable."