"We expect action, including legal action, against the people involved in the incident and also people responsible for instigating the incident," he said.
Prime Minister Modi after his arrival in the country was greeted by some groups protesting against atrocities in India.
On Wednesday, during the bilateral leg of Modi's visit to the UK, some protesters at Parliament Square turned aggressive during which the Indian tricolour was torn down from one of the official flagpoles set up for all 53 Commonwealth countries to mark the Commonwealth Heads of Government Meeting (CHOGM) and ripped up by some protesters.
The perpetrators, caught on camera, were pro-Khalistani demonstrators brought together with Kashmiri separatist groups under the banner of the so-called 'Minorities Against Modi' group, led by Pakistani-origin peer Lord Ahmed.
There is growing pressure on the UK government to act against Ahmed, who is seen as repeatedly "instigating" violence against India on UK soil.
A UK Foreign and Commonwealth Office (FCO) spokesperson said the UK government had been in touch with the Indian High Commission soon after the incident.
"While people have the right to hold peaceful protests, we are disappointed with the action taken by a small minority in Parliament Square and contacted High Commissioner Yashvardhan Kumar Sinha as soon as we were made aware," a spokesperson said.
Scotland Yard also issued a statement following the protests and confirmed that it is investigating the incident involving the Indian tricolour being pulled down.
"Police are investigating after an Indian flag in Parliament Square was pulled down at 1500 [UK time] on Wednesday, 18 April. The flag has been replaced. There have been no arrests. Enquiries continue," a Metropolitan Police statement said.
A senior broadcast journalist from one of the leading Indian media channels covering the protests, who was caught up in the scrum, has now also registered a formal police complaint with the Met Police.
"To my shock, the protesters while raising anti-India slogans brought the Indian flag down, tore it with scissors until it was completely destroyed...Within seconds, I was pushed, abused and intimidated," Loveena Tandon, who represents Aaj Tak news channel in the UK, said in a statement.
"A message must be sent to all those out there that we journalists make people aware of what is going on in the world. Shutting us up or being violent towards us defeats their own purpose of being heard," she said.
The incident also went viral on social media, with people expressing their shock and support to the journalist who was caught up in the incident.
The groups involved were seen with "Free Jaggi" posters and T-shirts, calling for the release of Jagtar Singh Johal who is lodged in a Punjab jail over his alleged involvement in the targeted killings in the state.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)