Teresa Cheng fell and was treated for an arm injury in hospital after being jostled by about 30 supporters of Hong Kong's pro-democracy movement.
Chinese official Geng Shuang said some in the UK "supported violent acts... to create chaos" in its former colony.
Hong Kong has been racked by five months of anti-government protests.
The campaign started in opposition to a now-withdrawn plan to allow extradition to mainland China, but it has since morphed into wider demonstrations backing democracy and opposing the actions of the police.
The protests have continued unabated - Friday was the fifth consecutive day - and have often turned violent. On Thursday, a 70-year-old man died after being hit by a brick thrown during clashes. A murder inquiry has been opened.
Hong Kong meanwhile confirmed it had entered its first recession for a decade, with the economy shrinking 3.2% in July to September, compared with the previous quarter.
More about: China