It said the raid occurred as regulators investigated fixing fears of the eurozone equivalent of the scandal-hit, London-based Libor inter-bank lending rate.
The search was ordered by prosecutors in the southern city of Trani, who have opened a criminal probe into the possible manipulation of the Euribor rate.
The move comes after complaints were filed by two consumer groups, Adusbef and Federconsumatori. Two judicial sources also confirmed the raid occurred last week, according to Reuters.
Documents, computer material and emails were seized, the consumer groups said in a joint statement.
They said the Milan raid occurred “with the aim of looking for evidence that Barclays also manipulated Euribor, as it did with Libor, with a negative impact on mortgage rates paid by Italians”.
Barclays was forced to pay a total of £290m in fines to UK and US regulators after it admitted fixing its Libor rate for commercial advantage.
The scandal forced the resignation of chairman Marcus Agius, chief executive Bob Diamond and chief operating officer Jerry del Missier. All three men were later quizzed by MPs on the Treasury Select Committee.
The Libor scandal has sent shock waves through global banking, and embroiled both US Treasury Secretary Timothy Geithner and Bank of England governor Sir Mervyn King in the controversy.