South Yorkshire's chief constable has said the force "regrets" that Sheffield's tree protests have led to arrests of "decent people".
Stephen Watson said police had "bent over backwards" not to make arrests at protests over the felling of thousands of trees by city council contractors.
Twenty-five tree protesters have been arrested since early January.
Meanwhile, an investigation into the alleged poisoning of contractors has been dropped with no charges brought.
The felling is part of the £2bn 25-year Streets Ahead project and has seen about 5,500 trees removed since 2012.
The council says the trees have been assessed as dead, dying, diseased, damaging or dangerous, and each tree cut down will be replaced, but protesters say healthy trees have also been lost.
South Yorkshire's Police and Crime Commissioner (PCC) Dr Alan Billings quizzed Mr Watson at a public accountability board meeting about the force's handling of the bitter protests.
Mr Watson said contrary to accusations, the force had not colluded with the council or contractors Amey.
He said: "It is a source of regret to us that in these protests, we have an element of people of good character and decent people who have found themselves coming into contact with the law.
"We do not want to arrest people and we do not want to criminalise people.
"My plea is that if you are being warned you may be arrested, be sensible."
Some, including pensioners, have been arrested for breaching the peace. Others were accused of aggravated trespass, assault and criminal damage. Not all have been charged.
Costs to the police have risen and pressure has been growing on the council to find a solution.
Mr Watson told the PCC that up to 33 officers were on-hand for crowd control duties each day, plus an experienced senior officer for command duties.
As a result, officers had been lost to other duties.
He said the force was not "an agent of Sheffield Council, Amey or protest groups" but "absolutely impartial".
The felling has been halted over Easter to allow talks between the council and Amey.