In the spring, before the selection row broke, the union chief launched an attack on Ed Miliband, warning he would be "cast into the dustbin of history" unless he abandoned support for Blairites Jim Murphy and Douglas Alexander. The Labour leader branded the attack reprehensible.
Without naming names, Mr McCluskey insisted some senior Labour figures had made "disgraceful" allegations against Britain's biggest union over the Falkirk fiasco, of which they "should be ashamed".
The union chief said: "There's no doubt there's been damage. The task is to try and repair that damage. I suspect the public are fed up with Falkirk.
"The Labour Party in Scotland has a huge challenge with the SNP and the independence debate coming up. Labour has to start demonstrating they are on the workers' side. They should be concentrating on that; any internal machinations within the party should be forgotten."
Mr McCluskey denigrated "smearmongers who continue to try to stir it up", naming Falkirk's independent MP Eric Joyce, "the disgraced MP who in a drunken brawl brought shame on the Labour Party and Falkirk, is suddenly the moral compass for us all; that's a bit of a joke".
Labour's conference on party reform will take place in March.
l On sale at the conference: mugs with Baroness Thatcher looking like a vampire with the words: "I still hate Thatcher".