"I do not want to comment on that."
Translation:Jeg vil ikke kommentere det.
Is there a good rule to remember when to use "å kommentere på" and just "å kommentere"? For example, "Hun kommentere på bloggen hans" vs. "Jeg vil ikke kommentere det"? Both have the english translation "to comment on (noun), but one uses the "på" construction and the other does not.
In the sentence, "Hun kommentere på bloggen hans," the på means at, really, meaning at the location of, and has nothing to do with kommentere grammatically speaking.
"Hun kommentere på bloggen hans" =
"She + is commenting + on/at/at the location of + his blog."
"Kommentere" is not typically joined with nouns by prepositions.
Like Luke51991 said, you comment on a blog or forum ("kommentere på"). However, you will also find both "kommentere" and "kommentere på" in other situations, meaning just to comment. I cannot find an official article about this , but found one for Danish where it says the addition of "på" is by some seen as a mistake (it certainly is superfluous) which came into the language around 2010 and it has been taken from the English "to comment on". If you say "Det vil jeg ikke kommentere" in a harsh tone, it would be taken to mean the same as the "No comment" (Norwegian: "Ingen kommentar") you often hear from lawyers, police and politicians.