Funny you should ask. This thread in the German subsection of the forum is about automating the use of PDF Squeezer, which would apparently do what you are asking after. The OP set up an automator action/app with the required settings, and I wrote a script to automate sending PDFs to that app. We ran into some trouble, and I haven’t yet received feedback on my latest suggestion. But perhaps you want to tag along with the idea.
Adobe Acrobat is scriptable, so you may also be able to write a script to automate things using Acrobat; I haven’t scripted Acrobat myself, so I’m not going to be able to provide you with a ready script as far as that goes. This script would be a suitable basis though, but you’d need to substitute the tell application Autokomprimierung section with the appropriate code for Acrobat.