Courteney, who starred in the popular 90s sitcom as Monica Geller, also revealed that she hasn't managed to arrange a full cast dinner with her former co-stars in the last 10 years.
Courteney, who arrived with her Snow Patrol boyfriend Johnny McDaid to The Late Show with David Letterman studios in New York, said that a reunion of any kind was unrealistic.
Speaking on the US chat show on Monday (21 April), Courteney was asked the now-common Friends reunion question, following constant rumours (for a good few years now) that a reunion, or movie version, is in the works.
"It's not gonna happen," she said. "Let me tell you something, there are six 'Friends' and I've been trying to put together a cast dinner for ten years. It doesn't happen.
"I can get the girls, maybe Matthew Perry, Matt LeBlanc cancelled last time, right at the last minute, Schwimmer lives here....so it's never going to happen."
Courteney starred in Friends along with Jennifer Aniston (Rachel Green), Matthew Perry (Chandler Bing), Lisa Kudrow (Phoebe Buffay), David Schwimmer (Ross Geller) and Matt LeBlanc (Joey Tribbiani).
The sitcom, which was on air for 10 seasons from 1994 until 2004, revolved around a group of friends from Manhattan.
Last year, Matthew and Lisa revealed that they wished Friends had lasted longer.
£2.49/month – that's all is costs for 4 issues of the REVEAL early edition. Gossip too good to wait for! Subscribe today!