The Twilight star said that he advised the singer to reach for her goals, not taking into account that she has already achieved worldwide success.
"Actually I had this argument with Adele, which is probably the most ridiculous thing I've ever said," Pattinson told Movieline. "I was saying, 'You know, you can really just like reach for it (her goals)', and she was like, 'You do realise I am like the biggest-selling female artist ever?'
"And I just for some reason just decided to get into an argument with her. [I woke up the next morning] kind of really, really regretting every word I said."
The actor also confessed that he once thought his fame made it difficult to hold conversations with "random people" before realising that he has always had trouble.
"You kind of, you have all these fantasies if I wasn't famous I'd meet all these random people in the street all the time.
"But you don't meet random people in the street," he continued. "Most of the time you're trying to avoid everybody even if you're not famous."
Pattinson previously admitted that he nearly abandoned acting after he became famous from his role in The Twilight Saga.
> Robert Pattinson: 'Cosmopolis sex scene made me cringe'
Watch a trailer for The Twilight Saga: Breaking Dawn - Part 2 below: