Sikhs for Justice (SFJ) said its Facebook page had more than 85,000 followers and cannot be accessed by the internet users in India.
SFJ alleged that blocking its Facebook page was an attempt by the Indian government to curtail the spread of its message for a referendum in Punjab in 2020.
During the April visit of Prime Minister Narendra Modi to Canada, SFJ had filed a petition with the Canadian Prime Minister urging him to ask his Indian counterpart to hold an independence referendum in Punjab.
Being a US-based company, Facebook must comply with the US laws which protect freedom of speech and expression, it said.
"Facebook's act of blocking access in India to SFJ's page is arbitrary and will be challenged through legal action in the United States," Pannun added.