At a news conference during which he also announced his ticket for south Lebanon elections on 5 June, Berri said the law is the lesser of two evils.
But one of the priorities of the new parliament, he said, will be to draw up a modern law that will be acceptable to all Lebanese.
Efforts to come up with a new election law based on smaller districts were stymied when Berri declined to open a legislative session to discuss a new law.
Berri is expected to fare better under the old arrangement and some opposition members are thought to have quietly condoned Berri's move to ensure their re-election as well.
Lebanese Christians led by the influential Maronite Church have demanded the election law be changed to create smaller voting districts before the elections.
Christians, who account for 30% of the population and have opposed Syrian dominance, allege that the 2000 election law sets voting districts in a way that favours Muslim voters and Muslim candidates' lists.
At the moment, Christians and Muslims have an equal share of seats in the 128-member legislature.
Maronite leaders say the election
law favours Muslims
Meanwhile, Berri defended his Resistance and Development election ticket, saying it represents the south and southern families.
For the south Lebanon election, Berri, leader of the pro-Syrian Amal militia, has teamed up with Shia Muslim rivals of the Hizb Allah group to forge joint tickets likely to sweep votes in the area and return many of Syria's allies to parliament.
The election has divided the anti-Syrian opposition, which united many Christians and Muslims in rejecting Syrian dominance after the 14 February assassination of former Prime Minister Rafiq al-Hariri.
Elections are scheduled to begin on 29 May and run until 19 June.
Some politicians have suggested postponing them until a new, more representative election law can be drawn up while others have hinted at a possible boycott.
But the United States, the European Union and the United Nations - which all pressured Syria to withdraw all of its troops from Lebanon last month so unimpeded elections could be held - have demanded voting be held on time.