Three members of campaign group Extinction Rebellion(XR) have been interviewed by police over the action near land off the B4568 at Ael Y Bryn between Caersws and Aberhafesp in Mid Wales.
They were spotted at the entrance to the field on March 18.
XR Machynlleth member Victoria Bamford, who was part of the group responsible, said the move followed concerns that the nets would stop birds from nesting in the hedge before a scheme for the site was approved.
Montgomery-based Powys Crematorium Limited has lodged plans to build a facility on the field which the activists do not object to.
The company said the netting was installed to protect wildlife in the event of the development getting the go-ahead and that it should not to be interpreted as pre-empting the planning process.
Ms Bamford, 72, of Machynlleth, said: "We decided to go and take the netting off because nothing had been done about it since this issue was raised and the nesting season is due to begin.
"Three of us went to take it all off. There was a degree of 'aggro' involved. We started in the daylight, but it was dark by the time we finished.
"While we were still there some men and a woman turned up in dark coloured vehicles. They were really mad. They called the police who came and took photos.
"The officers asked us to make our way to Newtown Police Station were we were interviewed. They said they were looking into the matter and would be contacting us at a later date about whether charges will be laid.
"We don't know if the netting has been replaced since then because we saw three more rolls of it in the field.
"We want to make it clear we do not object in principle to the crematorium plan, but we don't like this netting as we feel it affects wildlife."
Dyfed-Powys Police stated: “We were called at 6.50pm on March 18 to a report of damage being caused on land adjacent to the B4568 between Caersws and Aberhafesp. Three people were voluntarily interviewed and then released while police inquiries continue.”
Campaign for the Protection of Rural Wales and the RSPB are among organisations campaigning against the bird netting and a petition calling for the end of use of such materials has so far attracted 365,000 signatures.
The plans for the crematorium development include providing a green burial site as well as create a garden of remembrance, new and improved access arrangements and car parking area.
Powys Crematorium Ltd said there were plans to plant new hedgerows as part of the proposed designs.