Footage posted online shows the thugs shouting and gesturing at the man before pushing him out of the carriage when he steps in.
Chelsea have vowed to support criminal prosecutions, but a fan who was on the train claimed the man was pushed because he was a Paris St Germain (PSG) fan rather than for being black.
The fans were travelling to the Parc des Princes ground for Chelsea’s Champions League match against PSG, which ended in a 1-1 draw.
They also chanted at bemused onlookers “We’re racist and that’s the way we like it” and “Where were you in World War Two?”
A Scotland Yard spokesman said: “The Metropolitan Police Service takes offences such as this very seriously, no matter where they occur. We will examine the footage with a view to seeing if we can apply for football banning orders, preventing people from travelling from future matches.
“We will, of course, assist French authorities to identify the people involved and support them in any action they choose to take.”
Season ticket-holder Mitchell McCoy, 17, from Fulham in London, was among 40 or 50 Chelsea fans on the train when the incident was filmed by British expat Paul Nolan.
Mitchell said: “We got on the train and at the station where the man was trying to get on we stopped for a couple of minutes. He tried to get on and a few people were pushing him off because there wasn’t much space on the carriage. You couldn’t move. People were saying it was because he was black. It’s not true at all. I personally think it’s because he was a PSG fan. Obviously they didn’t want him anywhere with us.”
Chelsea officials said they are working with the authorities to see if those involved have season tickets or any other connection to the club.
Sepp Blatter, president of football’s world governing body Fifa, tweeted: “I also condemn the actions of a small group of Chelsea fans in Paris. There is no place for racism in football!”
TV pundit and former England captain Gary Lineker said: “Just saw the video of the Chelsea mob’s deplorable behaviour and racist chants. Sickening, embarrassing, moronic, disgraceful.”