"The target was Le Jardin restaurant. We don't know yet if there were any casualties," a Western official told AFP.
The Taliban claimed responsibility for the attack.
The blast is the latest in a series of attacks around Afghanistan in recent weeks.
It came just days after Pakistan's powerful army chief General Raheel Sharif visited Kabul to try to prepare the ground for fresh peace talks with the resurgent Taliban.
Both sides agreed to hold a first round of dialogue between Afghanistan, Pakistan, US and China on January 11 to lay out a comprehensive roadmap for peace, officials in Kabul said.