In the video posted online, the al-Qaeda chief promised to spread Islamic rule and "raise the flag of jihad" across the Indian subcontinent. The message has been labelled as authentic and warnings have been sent out to local governments.
"We are taking the matter very seriously. Such threats can't be ignored, we have asked the states to be on alert (especially) Gujarat, Madhya Pradesh, Uttar Pradesh and Bihar," an Indian intelligence source told AFP news agency after Wednesday's video announcement.
The timing and content of the video suggests rivalry between al-Qaeda and its more vigorous rival in Syria and Iraq, the Islamic State group, which anecdotal evidence suggests is gathering support in South and Southeast Asia. Zawahri's announcement made two references to Gujarat, the home state of India's new Prime Minister Narendra Modi, a Hindu nationalist who has been a hate figure for armed groups because of religious riots on his watch in 2002. Over 1,000 people, mostly Muslims, died during the violence.
There has been no proof of the group's presence in India, while media reports claimed that Islamic State pamphlets have been distributed in Pakistan recently.
Zawahri went on to describe the formation of "al-Qaeda in the Indian Subcontinent" as glad tidings for Muslims "in Myanmar, Bangladesh, Assam, Gujarat, Ahmedabad and Kashmir" and said the new wing would rescue Muslims there from injustice and oppression.
A senior police official said that Gujarat has been high on the list of armed groups, including al-Qaeda, since the 2002 riots. Muslims make up 15 percent of the Indian population, numbering an estimated 175 million, but theirs is the third-largest Muslim population in the world. Some protesters in India-admistered Kashmir were seen raising Islamic State flags in July.
Kashmir, which is claimed by both India and Pakistan, has long attracted foreign fighters as well as home-grown rebel fighters against Indian rule.