The pledge is taken by Indian embassies and missions around the world to coincide with former prime minister Rajiv Gandhi's death anniversary on May 21, marked as Anti-Terrorism Day in India.
This year's pledge in London was organised as a wider event to involve Indians based in the UK.
"Thescourge of terrorism affects innocent lives not just in one country but across the globe. Nocountry and no people should shelter terrorists, promote terrorists or appease terrorists," said the Indian High Commissioner to the UK, Yashvardhan Kumar Sinha, before he led the community leaders and mission staff in taking the pledge at India Place here.
"We pledge to uphold and promote peace, social harmony and understanding among all fellow human beings and fight the forces of disruption threatening human lives and values," it reads.