11:50 AM PT -- A Delta spokesperson tells TMZ ... "As a global airline that brings people across the world together every day, Delta values diversity in all aspects of its business and has zero tolerance for discrimination." We're told Delta condemns the allegations in the suit and will defend itself against them.

Delta Air Lines doesn't just treat Jewish people unfairly, it also punishes its flight attendants who are friendly with them ... according to a new suit.

Four Delta flight attendants from New York -- with work experience ranging from 10 to 40 years -- are suing the airline for what they call "a pattern of intentionally discriminating and retaliating against ethnically Jewish, Hebrew and/or Israeli employees and passengers" ... specifically on the flight they worked from NYC to Israel.

Among the allegations of rampant anti-Semitism -- Delta fired a female flight attendant in March 2017 because she was Jewish, but tried to say it was because she missed a flight ... even though she was granted FMLA leave for a medical emergency.

Another female flight attendant -- who's not Jewish -- claims she was suspended without pay and demoted because she shared her Delta "Travel Companion" pass with a Jewish friend. Delta allegedly claimed the flight attendant didn't know her travel companion so she violated company policy, but she claims she's been friends with the man for 40 years. She alleges Delta investigated her and took away her travel benefits simply because her pass was given to a Jewish person.

Other allegations include being passed up for deserved promotions and a "hostile" and "intimidating environment" on the Israel flight.