The renowned Italian fashion duo compared the work she does to that of high street giants Zara and H&M, and said that she came into the fashion industry "after many, many, many different things".
While speaking to reporters at a fashion event at the Victoria and Albert Museum in London, Stefano Gabbana said: "She's a friend. She make a good job but... for us, she don't make the same way like a fashion designer.
"She become after many, many, many different things. She's a designer but..."
When asked if he was a fan of Beckham's designs, he replied: "She's a fashion designer but it's another... it's different. John Galliano is a designer... Alexander McQueen."
Domenico Dolce added that Beckham, Zara and H&M were "professional" designers, adding that British and Italian fashion were "completely different".
He said: "[Italian fashion is] more cool, more trendy."
Gabbana added: "Vivienne Westwood is one of the most important fashion designers in the world."
