Hi @niks1!
Minification should be enabled on the AEM publish and potentially author instance. Once done - through the OSGI configuration Day CQ HTML Library Manager as outlined in the linked article - AEM delivers all ClientLibraries minified.
The Dispatcher has no active task in minification. What you need to do though is adding the adjusted URLs (including the ".min." selector) to the dispatcher filter rules to 1. allow the dispatcher to deliver the files and not block them and 2. potentially allow the dispatcher to cache the minified files.
You are requesting these files using the ".min." selector as mentioned in the referenced article, right? (See different URLs of ClientLibs [A] vs. [B] in that article)
[A] http://<host>:<port>/etc/clientlibs/granite/jquery/granite.js
[B] http://<host>:<port>/etc/clientlibs/granite/jquery/granite.min.js
While you're on it, I would also highly recommend to have a look at the Versioned ClientLibs feature of AEM ACS Commons. It will add a hash selector to the URL and ensure that you are always referencing the latest version of your ClientLibs. The Hash will change whenever the ClientLib changes, so you can cache existing ClientLibs files indefinitely on both, dispatcher and in the client/browser.
If this information is not what you were looking for, please provide some more details on what's "not working for dispatcher".
Hope that helps!