The Russian Civil War lasted from 1917 to 1922 (at least that's what wikipedia said) and pitched the Reds against the Whites. As far as I know, European powers were already wary of the Soviets due to a dislike of socialism in general, seeing it as a threat meant to be quashed.
Seeing as WWI ended in the closing months of 1918 with the Treaty of Versailles being signed in early 1919, that still left 3 years for the Entente to intervene in Russia and back the whites, so why didn't they?
Did the European nations believe that the Soviets were destined to fail and that the Whites would emerge as Russia's new rulers? Did they just not care? Or were they too militarily exhausted from the war to really do anything, even with US materials and supply flooding in?
The Entente powers did involve themselves to a degree. There where Americans and British in Archangel. Though the official reason they were there was protect supplies sent by those countries from falling into soviet hands. Ultimately, after the brutality of WWI, no nation could reasonably convince its population to get involved in a civil war that didn’t concern them.