The three men, named as Imad al-Khatib, Nader Hmadeh and George Batrouni, were kidnapped "on arrival in Baghdad" on Sunday, it said in a statement, without giving further details.
Khatib is a businessman, Lebanon's ANI news agency reported.
Kidnappings for ransom or for sectarian or political reasons were rife in Iraq following the US-led invasion of 2003 that toppled dictator Saddam Hussein, but they had become less common from 2015 onwards.