The police privately planned a concerted public relations strategy to try to play down the impact of a television documentary that showed two filmmakers being arrested near Donald Trump's golf resort in Aberdeenshire.

Internal emails obtained by the Sunday Herald reveal officers agreed to manage the broadcast of the film on BBC Two last October in a "low-key" way in an attempt to dampen public interest. They also prepared to receive complaints from the public. The multiple award-winning documentary, You've Been Trumped, featured footage of its director, Anthony Baxter, and producer, Richard Phinney, being taken into custody while filming at the Menie estate in July 2010. All charges were subsequently dropped, and the police made a partial apology.

After being screened in Scottish cinemas and at international film festivals, the film's TV premiere in October last year prompted a storm of protest about the police action. But emails released by the police under freedom of information law show they were doing their best to contain any damage the documentary might do.

Five days before the broadcast, the then assistant chief constable of Grampian Police, Simon Blake, emailed colleagues to say he was co-ordinating a response to the film: "The force should manage this issue in a low-key and proportionate manner. I would not seek to take a high-profile approach that would serve to escalate the matter."

He proposed the preparation of a police statement that would only be provided to the media "if asked".

The aim of the strategy was to "maintain public confidence in the Grampian Police staff who are portrayed in the film", he said. He also wanted to "reassure effected staff that the matter is being appropriately monitored and managed" and "respond effectively to any complaints made following transmission of the programme".

Other emails disclose that police officers were closely monitoring media coverage of the documentary, as well as a 2400-strong online petition calling for an investigation by the Scottish Parliament. "We're of the opinion that the interest is waning," wrote police inspector Lyn Ross five days after the broadcast.

The emails show the police drafting a statement in response to a screening of Baxter's film in Aberdeen on June 17 2011, as well as dealing with a freedom of information inquiry about the arrests.

The emails were released earlier this month as a result of an ongoing investigation by the Scottish Information Commissioner, Rosemary Agnew, into the police's refusal to provide information on the arrests. The Sunday Herald initially requested information in October 2012.

Baxter accused the police of failing to learn from what had happened: "These documents prove how the police are more worried about their reputation and covering up their actions at the highest level rather than learning lessons," he said. "Instead of managing complaints and attempting to keep the issue low-key following the BBC broadcast, a real investigation should have been ordered into the actions of officers, who forcibly arrested and jailed us simply for carrying out an interview and attempting to get to the truth."

Baxter has begun filming a sequel to his Trump documentary. It has been backed by development funding from the BBC and the Scottish Government's arts agency, Creative Scotland.

A spokeswoman for Police Scotland, which has now replaced Grampian Police, said: "The police always endeavour to respond to any incident in an impartial, appropriate and proportionate manner." said a police spokeswoman.

"The 'low-key' email was about how the police approached media interest in the film showing the arrests. The public would expect the police to adopt an appropriate and measured response to such queries and the police approach was to continue responding in this manner."