West Ham has promised to enforce life bans as the Football Association prepares to investigate crowd trouble.
The Hammers gave up a 2-0 lead to lose 4-2 in their second home league match at London Stadium, the converted venue for the Olympic Games in 2012.
The capitulation by Slaven Bilic's team sparked trouble among sections of the West Ham support.
Journalists and supporters present at the match questioned the readiness of stewards at the stadium to react to problems in the stands.
And the FA has since informed Omnisport it will be liaising with "the club and the relevant authorities" over the matter.
The club has threatened to enforce life bans on offending supporters found guilty of committing offences.
"West Ham United unreservedly condemn the behaviour of the individuals involved in incidents during today's fixture against Watford," West Ham said in a statement read.
"While these isolated incidents were quickly brought under control, this behaviour has no place in football and West Ham United will work tirelessly to eradicate such incidents.
"We are currently undertaking an immediate full review with all stakeholders. This includes police, stadium landlord and operator LS185, who are responsible for appointing and managing stewards and security, to ensure we eradicate such incidents moving forward.
"Our policy on this behaviour remains one of zero tolerance and we will work with the police and other stakeholders to identify the individuals involved.
"Once identified, they will be banned from attending any West Ham United fixture for life and we will request the courts serve banning orders to prevent these individuals attending any football."