Thatcher certainly thought it was a war speaking of "the enemy within" and using MI5 to combat the strike. And as I say the dubious tactics used at for example Orgreave certainly convinced the miners that they were in a war. As you say wars have rules, but soldiers break those rules, look at the court martial going on at Bulford now. As for the cops, you may have stopped believing them, but most of the right leaning media (especially the Sun) treated their word as gospel, especially where the Miners' Strike and Hillsborough are concerned,right up to the recent Downing Street shenanigans. They and the Tories seem to have now changed their tune somewhat.
None of this excuses murder.
Thatcher may have considered war to be an appropriate metaphor, as did people on the other side but it was just a metaphor. There was no excuse for violence on the part of the strikers nor much of the time by the police either.