Ich möchte es Ihnen nicht sagen.

English Translation

I would not like to tell you.

The translation here is misleading. The verb is not in the present tense.

You’re right.

Depending on whether you translate German to English or vice versa …

… the translation for “Ich möchte es Ihnen nicht sagen.” should be

I don’t want to tell you.

… the translation for (If I were him,) “I would not like to tell you.” should be

Es würde mir nicht gefallen, es dir zu sagen. (wenn ich er wäre.)