Go tell this to this jewish author writing for jewish media outlet. He is the closest to claiming it was "jewish war"

The war in Iraq was conceived by 25 neoconservative intellectuals, most of them Jewish, who are pushing President Bush to change the course of history.

https://www.haaretz.com/2003-04-03/ty-article/white-mans-burden/0000017f-e398-d804-ad7f-f3fa5d520000

To address the Gallup poll results, the most plausible explanations seems lack of nationalism on part of jews. After 9/11 everyone was riled up for revenge to invade some arab country but obviously you won't feel that way if you don't feel any affinity to America in the first place. This explains why the two groups least in favor of the war were blacks and jews. Blacks because they think America is racist and jews because they think nationalism is stepping stone to nazism - unless it's nationalism towards Israel obviously.

nd this isn't just because it was a "Republican" war and most Jews are Democrats. Jews were less supportive of the war than non-Jews regardless of party affiliation.

This is not exactly what the poll said. They only split party affiliation by democrat and non-democrat. In other words jewish centrists+republicans vs. gentile centrists+republicans. Obviously there will be larger share of republicans in the latter.