The attitude of 'Red Scare' came with a general distrust of immigrants and hatred towards who was not of majority demographic of US.
Step-by-step explanation:
Until the 1920s, the US had one of the easiest immigrant laws and was a fairly welcoming country for all sorts of people who went and settled there.
The image of the cultural melting pot however, was gone by the beginning of the 1920s when the country became conservative and wary of anyone who came from outside that was not either from US or from specific countries.
Any person who was not considered of the white race was seen as different.
The scare of a communist revolution had changed the government and made their policies more conservative.