In a unanimous vote, the 15-nation council voted to extend the work of the peacekeeping mission, which began in 1978, until the end of July, when it will again come up for review.
In approving six more months for its peacekeeping mission in Lebanon, the council backed the latest report by UN Secretary General Kofi Annan and said it was concerned about the "tensions and potential for escalation" in the volatile border area.
It underlined that the force was intended as an 'interim' measure and called on both Israel and Lebanon to avoid cross-border violations.
It also pressed Lebanon to extend its authority throughout southern Lebanon, parts of which remain in the hands of the militant group Hezb Allah. But Beirut has indicated it will not do so until a peace deal is agreed with Israel.
The presence of Hizb Allah, which is backed by Syria, continues to be a major stumbling block in relations between Israel and Syria.
The number of UN peacekeepers has been cut to around 2,000 since Israeli forces left southern Lebanon in May 2000.