Why Tiffani Thiessen Won't Be a Part of 'Beverly Hills, 90210' Reunion Series (Exclusive)

The actress opened up to ET at the premiere of 'The Secret Life of Pets 2' in Los Angeles on Sunday.

A reimagining of Beverly Hills, 90210 is headed for TV with a slew of original stars, but fans shouldn't expect to see Tiffani Thiessen joining in on the reunion.

ET's Kevin Frazier spoke with Thiessen at the premiere of The Secret Life of Pets 2 at the Regency Village Theatre in Los Angeles on Sunday, and the actress said that she "sadly" won't be able to be a part of the new series.

Thiessen -- who starred as Valerie Malone for six seasons, and joined the series around the time of Shannen Doherty's departure in 1994 -- told ET that her current contractual obligations on her Netflix series, Alexa & Katie, will be keeping her busy for the foreseeable future.

"I'm actually shooting season three of Alexa and Katie right now. So I am working at the moment and busy," Thiessen shared. "I'm literally in the middle of my season, and I go 'til September."

As for the upcoming series itself, Thiessen said, "I don't know too much about it but I know people are going to be excited."

"My shoot schedule sadly won't allow [me to be apart of it], but I wish them well," she added. "I'm sure it's going to be great."

For more on the upcoming series, and some of the behind-the-scenes drama surrounding the reimagined revival, check out the video below.

Meanwhile, The Secret Life of Pets 2 opens in theaters nationwide on June 7.