"We will activate more helplines to be of further assistance to families and friends of those affected by attack," the High Commission said in a statement on Twitter.
"Any Indians injured in Manchester attack today may reach off-office hours of Public Response Unit of HCI (High Commission of India) ASAP at 0207632 3035," the statement said.
A suicide bomber blew himself up at a crowded arena hosting US star Ariana Grande's pop concert in Manchester, killing at least 22 people and injuring 59 others, the deadliest terror attack in the UK since the 7/7 bombings of 2005.
"We have been treating this as a terrorist incident and we believe that while the attack last night was conducted by one man, the priority is to establish whether he was acting alone or as part of a network," said Chief Constable Ian Hopkins of Greater Manchester Police.
The Indian High Commission in London had yesterday organised a community-wide event to mark Anti-Terrorism Day, coinciding with former Prime Minister Rajiv Gandhi's death anniversary on May 21.
"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," Indian High Commissioner to the UK Yashvardhan Kumar Sinha said at the event, during which he led an anti- terrorism pledge.