NFLPA Executive Director Maurice Smith told SI.com he saw the video and found it "disturbing."
Smith said he hadn't spoken with NFL Commissioner Roger Goodell yet, so he didn't comment on Rice's suspension.
"As a father, as a husband — when you see something like that, it's jarring. It's disturbing," Smith said. "For our union and for our players, it's one of those things where you at least try to look at something positive. And that is the reminder how unacceptable any kind of violence, especially domestic violence, should be. It has no place in our lives, and certainly in our community. And that's where we are right now."
The NFL indefinitely suspended Ray Rice Monday after video publicly surfaced of the Ravens running back violently assaulting his then-fiancée in a casino elevator.
The suspension follows weeks of backlash over the league's initial two-game suspension.
It's unclear whether the NFLPA, the players' union, will try to appeal Rice's suspension. So far the NFL Players Association has stayed mum on the situation. Several NFLPA staff members have not responded to BuzzFeed News requests for comment; two calls to NFLPA offices on Monday were not answered.
In the wake of the reaction to the initial suspension, Commissioner Roger Goodell wrote a lengthy letter explaining why the league's domestic violence policies were flawed and amended its guidelines. Then Monday, after new footage of the incident was released, the Baltimore Ravens released Rice from the team and the NFL suspended him indefinitely. The NFL allowed another player accused of domestic violence, San Francisco 49ers defensive lineman Ray McDonald, to play in their opener against the Cowboys on Sunday.
While the union has yet to publicly comment on Rice, it has been outspoken in its defense of other players who have been hit with suspensions for other offenses.
Most notably, the union has defended two high-profile wide receivers, Wes Welker and Josh Gordon, who were hit with suspensions for alleged drug use. Welker's four-game suspension was for an unknown drug, reportedly Adderall or Molly. Gordon was suspended for the entire season for smoking marijuana.
The NFLPA is already working to try to reverse their suspensions as it seeks new drug policies for all players.
"We want to get a new agreement in place but we understand the responsibility we have to the players and to the game," NFLPA President Eric Winston said in a statement last week. "It is critical that we get this right."
On Friday, NFLPA spokesman George Atallah tweeted at Sports Illustrated's Peter King to quell rumors about players hoping for an expedited change to NFL drug rules.
Atallah has yet to tweet about Rice.