It is the second police raid on the party's offices in a year as investigators try to determine whether FN used European Parliament funds to pay 20 assistants that were presented as MEP aides although they worked for the party elsewhere.
"It looks on the face of it like a media operation whose goal is to disturb the course of the presidential campaign," the National Front said in a statement posted on its website.
The raid comes three days after the EU's anti-fraud office OLAF said that FN party leader and European parliamentarian Marine Le Pen submitted a false employment contract.
The report said the parliament paid some 41,554 euros ($44,000) towards a contract for Le Pen's bodyguard Thierry Legier, who was falsely presented as a parliamentary assistant.
The European Parliament has previously accused Marine Le Pen of paying FN party staff with EU funds during the 2011-2012 legislature, saying that she defrauded it nearly 340,000 euros ($362,000).
Earlier this month, Le Pen missed an EU deadline to make an initial repayment of 298,000 euros ($316,000). She has denied any wrongdoing and refused to pay, saying that the allegedly fake job contract was part of an accounting adjustment. Britain's euroskeptic party UKIP faces similar allegations of funding domestic political campaigns with funds from the bloc it would like to dissolve.
Opinion polls put Le Pen ahead in April's first round of voting but show that she is unlikely to win in the run-off vote scheduled for May 7.
Le Pen's funding scandal has largely been drowned out by another fake jobs scandal engulfing her conservative rival Francois Fillon.
Fillon sunk notably in the polls after it allegations that his wife earned at least 680,000 euros ($721,600) for being his assistant in the French parliament - but never actually worked there. The conservative candidate has also denied the allegations.
rs/msh (Reuters, dpa, AFP)
French election campaign - battle of the outsiders?