Director Susanne Bier told Broadcast the script was "slowly being developed" for the follow-up.
Tom Hiddleston, Hugh Laurie and Olivia Colman starred in the BBC One thriller, which was a hit last year. Its three stars won Golden Globes, while Danish director Bier won an Emmy Award.
The series was based on John le Carre's 1993 novel - but the book does not have a sequel.
Bier told Broadcast: "We all very much want to do a season two, but the thing we absolutely do not want is to do something that does not live up to the level of season one.
"That would be a really bad idea."
She was discussing the drama at Keshet's INTV conference in Jerusalem on Tuesday.
More than nine million people watched the finale of The Night Manager on the BBC last March.
Hiddleston played enigmatic Jonathan Pine, who goes undercover to expose billionaire arms dealer Richard Roper (Hugh Laurie). Hiddleston has said he would consider making a second series.
Meanwhile, Le Carre announced on Tuesday that fictional spy George Smiley will return in a new novel - the character's first appearance in print for 25 years. A Legacy of Spies will be published in September.
The BBC is also adapting le Carre's The Spy Who Came in from the Cold, in which Smiley also appears, which will air next year.
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A second series of award-winning drama The Night Manager is in development.