Nepal failed to record win over India in the fifth attempt after losing four finals against the same opponent in international competitions.
Nepal conceded a goal in the first half followed by three more goals after the interval.
Kamala Devi scored the opening goal for India in the 32nd minute and added the second goal in the 56th minute.
Similarly, Bala Devi made it 3-0 in the 71st minute before Ashlata Devi scored the fourth goal in the 80th minute to help India win the goal medal.
In the last edition in 2010 in Dhaka, Nepal was restricted to silver after going down 1-0 in the final. Nepal's worst ever performance against India was a 6-0 drubbing in the final of 2014 SAFF Championship.
Despite having six experienced players -- skipper Anu Lama, Namita Dali, Bhagwati Thapa, Deepa Adhikari, Laxmi Paudel, Niru Thapa and Sajana Lama - who featured in the 10th SAG, Nepal failed to beat the host for the fifth time.
Nepal, which was unbeaten in the run-up to the final had played a goalless draw against India in the league match.
Nepal had defeated Bangladesh 3-0, the Maldives 2-0 and Sri Lanka 4-0 in the round robin league to qualify for the final as league winner. Nepal had secured final place after a draw against India in its penultimate match.