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 US 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.
The head of Lebanon's internal security force, Ibrahim Basbous, said the bomb had contained around 15 kg of explosive material and had been placed in a flower bed, the National News Agency said.
Interior Minister Nohad Machnouk said: "Politically it is clear that the target was Blom Bank only."
He said the attack had nothing to do with the militant group Islamic State, which has mounted suicide bombings in Beirut.
The last bomb attack to hit the Lebanese capital killed more than 40 people in November in the southern suburbs, an area where Hezbollah is dominant. That bombing was claimed by the Sunni Muslim Islamic State.
Finance Minister Ali Hassan Khalil tweeted that the attack had "targeted the stability of the whole of Lebanon".
Targeting Hezbollah's finances
Heavily-armed, Iranian-backed Hezbollah, which is classified as a terrorist group by the United States, wields enormous political influence in Lebanon and its powerful military wing is playing a major role in backing President Bashar al-Assad in the Syrian conflict.
The US Hezbollah International Financing Prevention Act (HIFPA), passed in December, threatens to punish any organisation providing significant finance to Hezbollah.
It has ignited a dispute between Hezbollah and a central bank widely seen as a pillar of the otherwise weak and dysfunctional Lebanese state.
The central bank has said the US law must be applied to avoid the international isolation of Lebanon's banking sector.
Hezbollah's parliamentary bloc issued a statement last week reiterating its criticism of the central bank's position, saying the US law infringed Lebanon's national sovereignty.
Hezbollah, whose fighters played a major role in forcing Israel to withdraw from southern Lebanon in 2000, enjoys strong support in the Lebanese Shi'ite community. Its members include government ministers, lawmakers and local councillors.
Sunni Muslim politician Saad al-Hariri, a former prime minister and leader of the Future Movement political party, condemned Sunday's attack at a party event. "Our battle with terrorism, bombings, killings, assassinations and direct and indirect messages is long … Terrorism will not intimidate the Lebanese."
