The incident took place on Friday (May 1) as the Labour candidate tried to question Tory Boris Johnson about the challenges faced by people in her constituency as he was campaigning with her Conservative rival Angie Bray.
The activist, who has been named locally as former vice chair of the local Conservative branch Karim Sacoor, was caught on video repeatedly trying to drag Ms Huq away from Mr Johnson.
He then appears to push Angie Bray leaflets in Ms Huq's face, as they walked in Churchfield Road, Acton.
Ealing Broadway councillor Seema Kumar was also photographed pushing leaflets in Ms Huq's face.
Ms Huq said: “Boris Johnson tries to create the impression he’s all positive and fun, but he can’t deal with any real scrutiny. I was trying to ask him serious questions about issues affecting Ealing, and to be grabbed and shoved around by his supporters is disappointing.
“Boris Johnson and his team owe me an apology – it’s about the example politicians like him set to people, particularly around how women are treated. You wouldn’t accept it in other walks of life, and people expect better from the Mayor of London."
Ms Bray tweeted on Saturday (May 2), saying: "It was unfortunately inexcusable even in heat of the moment and I have told him to step down from my team. We apologize to Rupa."
Julian Gallant, chairman of the Ealing Central & Acton Conservative Association, said: “I understand that during a walkabout, with Boris Johnson and Angie Bray in Acton, the Labour candidate appeared suddenly between Angie and Boris, forcing a female supporter into the road in the process.
“After trying to ask Boris several questions and after a few minutes she refused to walk away and allow the walkabout to continue.
“It was a political stunt and only after several minutes did a Conservative supporter place his hands on Rupa Huq’s shoulders to encourage her to leave.
“At no point was she dragged or assaulted and when she reached the corner she left Boris and his entourage entirely voluntarily. None the less, this was a regrettable situation and we have apologised to Rupa Huq and have asked the supporter in question to stand down from the campaign team, which he has done."
The chairman added that Ms Bray was behind and could not see clearly what was happening. He also denied that the Tory parliamentary candidate was smiling about the situation, as Ms Huq's team have claimed.