NEW YORK -- Calls for a boycott of the Academy Awards are growing over the Oscars' second straight year of all-white acting nominees, as Spike Lee and Jada Pinkett Smith each said Monday they will not attend this year's ceremony.

In a lengthy Instagram post, Lee said he "cannot support" the "lily white" Oscars. Noting he was writing on Martin Luther King Jr. Day, Lee -- who in November was given an honorary Oscar at the Governors Awards -- said he was fed up: "Forty white actors in two years and no flava at all," he wrote. "We can't act?!"

In a video message on Facebook, Pinkett Smith said she wouldn't attend or watch the Oscars in February. Pinkett Smith, whose husband, Will Smith, wasn't nominated for his performance in the NFL head-trauma drama "Concussion," said it was time for people of color to disregard the Academy Awards.

"Begging for acknowledgement, or even asking, diminishes dignity and diminishes power," she said. "And we are a dignified people, and we are powerful."

She added: "Let's let the academy do them, with all grace and love. And let's do us differently." The video had amassed 4.5 million by mid-Monday afternoon.

Last year's all-white acting nominees also drew calls for a boycott, though not from such prominent people as Lee and Pinkett Smith. The audience for the broadcast, hosted by Neil Patrick Harris, was down 16 percent from the year prior, a six-year low.

The Feb. 28 broadcast will be hosted by Chris Rock and produced by "Django Unchained" producer Reginald Hudlin and David Hill.

On Saturday, Rock, unveiling a new promotion for the broadcast, called the ceremony "The White BET Awards."

The academy didn't respond to messages left Monday.

When Oscar nominations were announced Thursday, Isaacs acknowledged she was "disappointed" all 20 acting nominees again were white. Isaacs has worked to diversify membership for the academy, which a 2012 study by the Los Angeles Times found is overwhelming white and male.

Many awards handicappers expected nominations for Idris Elba of "Beasts of No Nation" and Benicio Del Toro for "Sicario." The N.W.A. biopic "Straight Outta Compton" also failed to earn a best-picture nomination, despite some predictions it would. Ryan Coogler's acclaimed Rocky sequel "Creed" scored only a nomination only for Sylvester Stallone. (Lee's own movie, the Chicago gang violence hip-hop musical "Chi-Raq" -- celebrated by some and scorned by others -- also went unnoticed.)

The hashtag "OscarsSoWhite," created last year, was quickly resurrected online following the nominations. The Rev. Al Sharpton -- who last year met with former Sony head Amy Pascal following leaked emails that some viewed as racist -- on Friday lambasted the academy.

"Hollywood is like the Rocky Mountains, the higher up you get the whiter it gets and this year's Academy Awards will be yet another Rocky Mountain Oscar," said Sharpton.

In his post, Lee made it clear the Academy Awards is only part of the problem in an industry with deep-rooted diversity issues. In his Governors Awards speech, Lee said "It's easier to be the president of the United States as a black person than be the head of a studio."

"The Academy Awards is not where the 'real' battle is," wrote Lee on Tuesday. "It's in the executive office of the Hollywood studios and TV and cable networks. This is where the gate keepers decide what gets made and what gets jettisoned to 'turnaround' or scrap heap. This is what's important. The gate keepers. Those with 'the green light' vote."