Donald Trump's clothing line has been hung out to dry by Macy's -- but he's firing back at the company for caving to pressure, and claiming it backs illegal immigration.
Macy's made it short and sweet, saying it doesn't "believe the disparaging characterizations portray an accurate picture of the many Mexicans, Mexican Americans and Latinos who have made so many valuable contributions to the success of our nation."
Trump immediately blasted his former biz partners -- saying Macy's and NBC dropped him at the first sign of trouble ... and he sees that as a sign they "support illegal immigration, which is totally detrimental to the fabric of our once great country."
Trump added one financial dig ... that his Macy's deal was a "small business" worth much less than his principles.
He was heavily involved with Macy's since his line was launched in 2004, even appearing in commercials.