The purported video of the incident surfaced on the social media and went iral on the internet, following which two persons have been arrested.
In the video, the couple can be seen being mercilessly threatened by a man with a stick in hand while the entire spectacle was watched by dozens of people.
The mob waylaid the couple in their 20s and assaulted them at Pukhurpur village in Rongjuli area on June 19, news agency PTI reported.
'We didn't receive a complaint but we took a suo motu cognizance of the case and have arrested main accused..," ANI quoted Assam Director General of Police Kuladhar Saikia as saying.
According to reports, both the man, 25, who is married, and the woman, 22, who is divorced, are local residents of the area.
The police have arrested one person on Thursday while another person was nabbed on Friday.
Both were booked under various IPC sections including 342 (wrongful confinement), 325 (voluntarily causing grievous hurt) and 354b (assault or use of criminal force to woman with intent to disrobe).
(With inputs from agencies)