The film, directed by Anurag Basu, also stars Ileana D'Cruz and Priyanka Chopra.
"All strain of work vanished after having just finished seeing 'Barfi'. Ranbir Kapoor a masterful brilliant performance... Priyanka, simply unbelievable, and Anurag Basu's extraordinary making," Bachchan tweeted.
Ranbir plays a deaf and mute character while Priyanka is seen playing an autistic girl in the film, which released to positive reviews last Friday.
"In 'Barfi', the lovely Ileana d'Cruz in her debut for Hindi film... such a mature and balanced performance... many congratulations," added Big B.
The 69-year-old actor also gushed about how Indian cinema is going through an exciting phase.
"Indian Cinema, its films, directors, actors, technicians going through a magical phase of a change over... such exciting times!!"