A commuter, identified in media reports as Souleymane S, appeared to be prevented from boarding a train by supporters travelling to the Parc des Princes for the Champions League draw with Paris St Germain.
Footage captured by a bystander shows Souleymane being pushed back on to the platform amid chants of ''we're racist, we're racist and that's the way we like it''.
Writing in the match programme for Saturday's Barclays Premier League clash with Burnley - the club's annual 'Game for Equality' - Terry offered his view on the incident.
"Football is a sport for everyone, that is one of the main reasons why we love it, and what happened on the Paris Metro was unacceptable," Terry said.
"The club has reacted quickly to deal with the situation and will continue to do so."
Terry was given a four-match ban and fined £220,000 in 2012 after being found guilty by the Football Association of racially abusing QPR defender Anton Ferdinand
Alongside that punishment, the regulatory commission in the case stressed that Terry was "not a racist".
Buck expressed similar sentiments to manager Jose Mourinho, who spoke out at Friday's pre-match press conference, by saying the club were "disgusted" and "appalled" by the racial abuse, adding that owner Roman Abramovich was also "disgusted".
"Tuesday night was a crossroads for us
Despite there only being a small group of individuals involved, it showed there is still work to be done to eradicate discrimination - in all its forms," Buck said.
"We are determined to do all we can to wipe it out."
Source : PA
Source: PA