Overview
Racists of Novigrad is an unmarked secondary quest in The Witcher 3: Wild Hunt, made up of two small street encounters in Novigrad. They show how hostile the city has become toward nonhumans. Normally the first one has to be done before the second appears.
The female elf
North of Portside Gate, at the second crossroads, two townsmen are harassing an elven woman they are sure is lying about something. She refuses to explain herself. If Geralt leaves, they insult her again and let her go. If he defends her, they back off, knowing they stand no chance. Whatever Geralt says, the elf answers with bitter sarcasm and walks away. A good deed does not buy much trust here.
The male elves
Near the dye pits northeast of Tretogor Gate, townsmen are harassing a group of elves. Standing up for the elves means killing the townsmen. Afterwards Geralt can warn them to leave the city before the Eternal Fire comes for them, or simply say goodbye. The elves are not grateful. They know their options are poor either way.
Note: this second encounter sits on the route of the chase in Contract: An Elusive Thief. Stopping to help the elves at that moment lets the thief escape and fails the contract.