The protesters were carrying flags of Pakistan-occupied Kashmir (PoK) and shouted "freedom" slogans.
David Vance of AltNewsMedia tweeted, "In London, UK Pakistanis attack the Indian High Commission. Why are these feral thugs allowed on our streets?"
He alleged that British Pakistanis are enjoying the support of the Scottish National Party.
"Many (UK) Pakistanis in Scotland are strong supporters of the separatist SNP (Scottish National Party). In return, the SNP is campaigning to reinstate Article 370 in Kashmir, so that non-Muslims there can continue to receive severely discriminatory treatment," Vance said in another tweet.
Many British people on Wednesday visited the Indian High Commission and accused London Mayor Sadiq Khan of allowing thousands of protesters to gather for an anti-India protest.
Katie Hopkins, a media personality and columnist, posted a video on her Twitter handle showing a filthy mess of eggs and vegetables thrown by the agitators.
She said, "The Embassy in London - one of our greatest allies - is a filthy mess of eggs and vandalised windows at the hands of Pakistani protesters in the UK. Is the Muslim Mayor of London enabling this behaviour? Why has this not been cleaned up? Deeply shaming for Britain."
This is the second time that violent protests took place over the Kashmir issue outside the Indian embassy in London. Earlier, the protests broke out on Independence Day on August 15.