Why? In the 1920's Communism was more weird than threatening. America was quite cozy with the Soviets considering. American industry were of great help to Lenin's economic reconstruction.
Given the US did send small combat expeditionary forces to fight the Bolsheviks before they even concluded the Russian Civil War and experienced its first Red Scare from 1917-1920, it is very unlikely a communist movement in Mexico would be treated kindly (especially given fresh US memories about Pancho Villa and US business interests that might be opposed to a program of nationalization in Mexico).