Prime Minister Narendra Modi said that India stands in solidarity with the UK.
"Deeply saddened by the terror attack in London. Our thoughts and prayers are with the victims and their families," Prime Minister Modi said, on social media platform Twitter.
"At this difficult moment, India stands with UK in the fight against terrorism," PM Modi added.
The terror attack in London was also condemned by President Pranab Mukherjee.
"Shocked to hear of terrorist attack in London; condolences to bereaved families and prayers for recovery of injured," the President tweeted.
Earlier, the Ministry of External Affairs said that no Indian casualty has been reported so far. The Indian High Commission in UK also issued helpline numbers to help its citizens in London.
The attack on the British parliament in London's Westminster area occurred on the busiest day of the week, when Prime Minister Theresa May appears for her weekly questions session and the House of Commons is packed with visitors.
"The location of this attack was no accident... The terrorist chose to strike at the heart of our capital city where people of all nationalities, religions and cultures come together to celebrate the values of liberty, democracy and freedom of speech," UK Prime Ministe Theresa May said.
(with inputs from Agencies)