United States lawmakers and influential Indian-Americans have condemned the attempted arson at the Indian consulate in San Francisco and called for expeditious action against those behind this "criminal act".

They also slammed the "violent rhetoric" against India's Ambassador to the US Taranjit Singh Sandhu and said free speech does not mean a license to incite violence or vandalise property.

A video by Khalistan supporters, dated July 2 and posted on Twitter, showed the act of arson at the Indian consulate in San Francisco.

The video, with the words "violence begets violence" emblazoned over it, also showed news articles related to the death of Canada-based Khalistan Tiger Force (KTF) chief Hardeep Singh Nijjar.

Nijjar, one of India's most-wanted terrorists who carried a cash reward of Rs 10 lakh on his head, was shot dead outside a gurdwara in Canada last month.

In a joint statement issued on Thursday, Congressmen Ro Khanna and Michael Waltz, co-chairs of the Congressional Caucus on India and Indian-Americans, said violence against diplomatic facilities will not be tolerated.

"As the co-chairs of the India Caucus, we strongly condemn the attempted arson and vandalism at the Indian Consulate in San Francisco and the posters circulating on social media with violent rhetoric aimed at Indian diplomats, including Ambassador Sandhu," they said.

"We support the right to free speech and freedom of expression for every American but that is not a license to vandalise property or incite violence. Violence against diplomatic facilities is a criminal offence and will not be tolerated. We urge the State Department to coordinate with law enforcement in their investigation of the damage at the Indian Consulate expeditiously and hold those involved accountable," they added.

Congressman Brian Fitzpatrick said the attack on the Indian consulate is unacceptable.

"I firmly condemn the repeated hateful attacks on the Indian Consulate and look forward to those involved being held accountable with appropriate legal action," he said.

Till Thursday, no action had been taken against those involved in the attack on the Indian consulate.

A spokesperson of the National Security Council of the White House said the US takes the safety and security of diplomats very seriously.

"We take very seriously the safety and security of diplomats living in the United States and strongly condemn acts of vandalism or violence against diplomatic facilities or personnel," the spokesperson told PTI.

Congressman Mike Lawler said the attempted arson at the Indian consulate was disturbing.

"I had the pleasure of welcoming Prime Minister (Narendra) Modi of India to Washington, D.C. last month and look forward to a continued, strong partnership with the world's largest democracy," he said.