The 57-year-old actor's lovelorn character was obsessed with Aniston's Rachel Green in the sitcom, and the pair worked closely together for a decade.
However, when filming wrapped in 2004 the two actors lost touch — although James insisted that it wasn't personal.
He admitted: "I haven’t seen Jennifer since the wrap party, honestly. It’s been 15 years since it ended.
"That was a time of our lives when we were lucky enough to be able to work together for 10 years and have that sort of chemistry.
"She lives in another city. I’m not going to go and hang outside her house and wait for her to come outside and say hello. That would be kind of weird!"
James added to the Daily Star Sunday: "It’s nothing personal. Actors move on. It’s been a long time."
With dark brown stubble and glasses, the star looked unrecognizable to the coffee-shop owner, who Rachel once described as having "hair brighter than the sun" in the show.
James isn't the only Friends alumni to be reflecting on his time on the show in recent days, with Cali Sheldon also marking the programme's anniversary with throwbacks to her time on set.
Cali and her twin sister Noelle shared the role of Rachel and Ross' daughter Emma between 2003 and 2004.
Taking to her Instagram page, 17-year-old Cali posted behind-the-scenes snaps, with one of the images showing her being cradled by onscreen mum Jennifer, and another a sneak peek at baby Emma's first birthday party alongside Jennifer and her co-stars, Courteney Cox and Lisa Kudrow.
"Friends" first hit our screens on Sept. 22, 1994 and ran for 10 years.
This article originally appeared in The Sun.