A bomb exploded outside the headquarters of Lebanese Blom Bank in central Beirut on Sunday, causing damage but no fatalities, the interior minister said.
There was no immediate claim of responsibility.
The Lebanese banking sector has been at the centre of an escalating crisis since the United States passed a law requiring banks to take steps to target the finances of the armed Shi'ite political group Hezbollah.
Lebanon's central bank has pushed its commercial banks to heed the U.S. act, and Blom Bank is one of those that has closed accounts belonging to people suspected of links to Hezbollah. The group had no immediate comment on the blast.
The Lebanese Red Cross said two people had suffered minor injuries in the blast, which took place around 8 p.m. in the Verdun area of Beirut, the National News Agency reported.
Local television showed footage of a damaged building, with one hole in a concrete wall, and said shattered glass had fallen to the ground from several storeys up.