Donald Trump isn't ruling out a third run for president ... and he's making it clear he has zero interest in being anyone's VP.

The prez spoke to reporters Monday aboard Air Force One en route to Japan ... when he was asked about Steve Bannon's recent comments, claiming there are plans for Trump to run and potentially win a third term in 2028.

Trump says "I would love to do it" when pressed about the potential presidential bid ... adding, "I have my best numbers ever."

A reporter follows up asking if he's "not ruling it out" ... and DT replies, "Am I not ruling it out? You'll have to tell me."

Trump then takes aim at the Democrats, saying, "All I can tell you is that we have a great, a great group of people, which they don't," before ripping into Rep. Jasmine Crockett and Rep. Alexandria Ocasio-Cortez ... referring to both as "low IQ."

Trump is then asked about a theory floating around that could keep him in the White House -- by running as vice president -- but he quickly shuts that down, calling it "too cute" and saying "it wouldn't be right."

Time will tell if he actually makes a run or just keeps teasing the idea ... stay tuned.