I think you may be referring to the "humans are a virus / human beings are a disease" dialogue ... "and we are the cure".

That refers more to human society, but yeah, why refer to yourself as "the cure" if you think of yourself as a superior lifeform who conquered and then even colonized the bodies of the former chief predator on the planet?

All of this getting back to: why not just make a fusion reactor or some such, and not bother with all that (bio-)mechanical machinery needed to harvest human "energy", even if we were a battery, that surely sounds more wasteful and inefficient?

On the other hand, human society went extinct so humans had no collective memory of the past - unless it could be found written somewhere, which we were not told of in the movie series - and also robot society may itself not even be aware of its own motivations. Machines are better at repeating patterns than truly "thinking", especially outside-of-the-box creative stuff (in movies, whereas irl machines don't "think" at all... yet), so it seems more plausible that Mr. Smith is purely spouting BS here to keep Morpheus' mind occupied while it can be hacked, maybe even believing his own crap, but all very minor in relation to fulfilling his programming-mandated mission (seemingly not knowing that a prior instantiation of him has done this before? or more likely not caring even if he did).

Anyway, this may be going too far since it is also highly plausible that even if the machines did want humans for batteries, the offer of a pleasant Ephesian Fields / Heaven type existence was not genuinely for the benefit of the humans (they seem to think at any rate), but rather to keep them docile & complacent.

Ultimately, it's art so it means whatever we want it to? :-P