The 25-year-old singer has been raising cash for survivors of the earthquake in Japan by selling We Pray For Japan wristbands for five dollars (£3.13), plus sales tax and a 3.99 US dollar (£2.49) shipping charge.
But a lawyer in Detroit is suing her over claims that she inflated the postage costs and kept the extra cash, and a spokesman has denied that there is any truth in the allegations.
Her rep told The Mirror, 'This misguided lawsuit is without merit and unfortunately takes attention away from the kind deeds of the fans around the world who are supporting the people of Japan.
'The entire five dollar donation made with the purchase of each bracelet is going to support the disaster relief. No profit is being made on shipping costs. Sales tax charges were made in accordance with local legal requirements.
'Lady Gaga has personally pledged her own funds to this cause and continues to support the victims of the disaster.'