Momentum says it has not received any complaints about its members being involved in a protest against a council’s adoption of a definition of antisemitism.
The pro-Jeremy Corbyn hard-left activism group said it would be willing to investigate and take action if necessary.
The definition was recognised by the government last year and is now widely used in the public sector.
A Momentum spokesman told the JC: “Momentum opposes antisemitism in all its forms.
“This council lobby was not organised by Momentum National. The local Momentum group in Haringey supported the lobby along with other organisations and some members attended.
“While we haven’t received any complaints about Momentum members present at the meeting, if we do we’ll investigate them and take the necessary, appropriate action.”
Two senior national Momentum members, Emine Ibrahim and Joseph Ejiofor, are councillors in Haringey and supported the motion.
Mr Ejiofor, the deputy council leader, last year posted a link on Twitter to a Jewish Socialists' Group article which claimed accusations of antisemitism in Labour were being "weaponised" to attack Jeremy Corbyn.
Joe Goldberg, a Jewish Labour councillor in the borough, said after the meeting that grassroots Momentum supporters had threatened him for supporting the motion.
Prior to Monday’s session, Haringey Momentum had encouraged members to attend and oppose the IHRA definition.
The group said it was working with Haringey Justice for Palestinians to oppose the “proposed adoption of the International Holocaust Remembrance Alliance guidelines on antisemitism.
“Some of the guidelines equate legitimate criticisms of the Israeli state with hatred towards Jews and therefore have the effect of suppressing support for the national rights of Palestinians.
“The campaign for councils to adopt these guidelines - which is not Labour Party national policy - has been ramped up in the context of the denigration of Corbyn's leadership of the Labour Party.”
