Watford are investigating an alleged incident of homophobic chanting during Saturday's match at Vicarage Road.
In a tweet the club said: "We have spoken to the supporter who reported this and are working with them to identify the individuals responsible.
"We reiterate our zero-tolerance approach to discrimination and how to report it."
Watford also posted on the club's official website that supporters who do not comply with their equality and diversity commitment face strict match-day punishment.
It said: "As part of this on-going commitment, the club would like to remind all supporters that racial, homophobic or discriminatory abuse, chanting or harassment is strictly forbidden and will result in arrest and ejection from Vicarage Road.