Luka clocked 1:59.19s to better the bronze medal she had won in this event in the previous edition of the Games in Guangzhou.
The gold was won by Kazakhstan's Mukasheva Margarita, who broke the two-decade-old Games record of 1:59.85s with a timing of 1:59.02s.
China's Zhao Jing settled for the bronze medal after finishing the race in 1:59.48s, which also happened to be her personal best.
The other Indian in fray, Sushma Devi ended fourth with a personal best timing of 2:01.92.