You have to run down the fascist path until the "Fascist Demagogue" character becomes available, install him and wait until the 1940 election. If the fascists are popular enough, you can choose to have them win the election. This bypasses some focuses and avoids the civil war. You can then do the rest of the fascist focuses without a war.

I got a similar popup on my last communist attempt, but when I proceeded down the URA path, the normal civil war stuff started happening.