The pair split last summer but appeared to be close recently when they were spotted together at a series of family and public events - and they spoke fondly of each other while promoting their film "Scream 4."
However, Arquette insists there are no plans for the couple to play happy families again in the near future.
During an appearance on pal George Lopez's late night show in America on Monday, the actor said, "We're best friends and we're family but people change. We're still working on ourselves and our relationship... but we're definitely not together now.
"If we were to get back together, we'd make a statement - so don't believe any stupid tabloids."