Grohl, who was the drummer for Nirvana which disbanded after Kurt Cobain's 1994 death, also released a lengthier letter in which he indicated not to expect more music in the near future.
While describing the last tour as a highlight of his career, the 46-year-old wrote: "You get that feeling that, if you're not careful, you'll run out of bread crumbs to find your way home and be lost in the woods forever.
"We could keep going. After all, we'd made it this far, right? What's another 20 years?" But he said that all good things must come to an end.
Addressing fans, Grohl wrote: "I can't help but wonder when we will see each other again. Who knows? But, with everything Foo Fighter-related, it will only be when it feels right. And that's a feeling that's easy to feel."
The tour had been due to end this month with dates in Europe including Paris.
But the band ended its tour early after the assault claimed by the Islamic State group that included a massacre of 89 people at an Eagles of Death Metal concert at the Bataclan.