Intended claims for injunctions have been served on several campaigners who have been trying to prevent the removal of some trees in the city as part of the controversial Streets Ahead road improvement programme.
Among those to be threatened with legal action are Green Party councillor Alison Teal, who today described the move as "Stalinist" after she was served with papers this morning.
She said: "Should I go to a tree protest my understanding is I could potentially be arrested or sued for damages. It feels quite a Stalinist action."
Coun Teal said she would be taking legal advice and has to respond to the council before July 12, when the authority intends to bring the case to the High Court in Leeds.
It comes as part of an increasingly bitter dispute which has seen 14 people arrested, including coun Teal, but no charges brought after the Crown Prosecution Service dropped all cases.
But Coun Bryan Lodge, Labour cabinet member for environment and street scene at Sheffield Council, said civil action was being considered due to “unlawful” disruption to street tree replacement work.
He said: “Following months of unlawful and costly disruption to street tree replacement works across the city by a small number of tree protesters, the council now has no alternative but to consider legal remedies to ensure these works can be completed.
“We continue to support the right to peacefully protest, and the majority of protesters who are doing so peacefully will not be affected. But there is a big difference between this and direct action which deliberately and unlawfully stops works from being carried out.
“Despite issuing representatives of the tree protester group a letter several weeks ago confirming that their actions remain unlawful, works continue to be disrupted, causing city-wide delays to the programme and against the wishes of residents."
Contractor Amey is tasked with maintaining the city’s 36,000 roadside trees as part of the Streets Ahead road maintenance agreement. Campaigners claim healthy trees are being unnecessarily destroyed but the council says the work is required to remove diseased, damaged or dangerous trees.