Aamir suffered the injury on November 14 night while shooting a wrestling scene. He is now returning to Mumbai to take a break from filming the movie directed by Nitesh Tiwari.
Aamir Khan took to Twitter to assure his fans and wrote, "Hey guys its not such a major injury. My back muscle has gone into a spasm. A week of rest and I will be back on shoot."
"Following the injury, Aamir took 24 hours of rest in Ludhiana as he could hardly move. Now, he has been asked to take complete rest for eight days after which doctors will decide the next course of action," Aamir's spokesperson told IANS.
The unit of the film, which also stars Sakshi Tanwar, Fatima Sana Shaikh and Rajkumar Rao, is on a break until Aamir is able to resume work.
Since it was Diwali time, his wife and filmmaker Kiran Rao and son Azad were with him in Ludhiana, when the injury struck.
'Dangal' is said to be based on the life of wrestler Mahavir Phogat.
It is yet another of the superstar's films to release on Christmas weekend -- a time when he also scored hits with 'Taare Zameen Par', '3 Idiots', 'Dhoom: 3' and 'pk'.