If you mean make something seem less important or to treat as insignificant, the verb trivialize is good.
Such jokes trivialize a legitimate health problem. Please be more thoughtful.
Judging from your use of compound, I think you might be after words such as mitigate, attenuate, and extenuate. All three mean to reduce in severity.
[i]The testimony served to extenuate her crime. The judge seemed more understanding after learning the circumstances.
Our financial peril has attenuated.
Your volunteer work has mitigated our staffing crisis. Thanks so much.[/i]
You might also try abate and subside. If you want to be plainer in describing something singular, you can try decrease. I stress singular because it will appear to indicate quantity rather than degree before plural nouns. There is also lessen. Such words are understood to mean decrease in severity before anything obviously bad.