Celine Dion -- I'm Passing on the Caesars

Celine Dion is NOT coming back to Vegas ... at least till the end of this year ... TMZ has learned.

The plan was ... Celine would return to Caesars Palace in March after taking a hiatus last August to care for her ailing husband.

Our Caesars sources say Celine has informed the venue the earliest she will return is most likely at the end of the year. She will not give a date.

We're told Celine continues to care for Rene Angelil, her husband of 20 years. He's battling throat cancer, but we are told he is getting better.

Caesars continues to fill The Colosseum with other acts ... including Rod Stewart, Elton John, Shania Twain, Reba McEntire and Brooks & Dunn.