"I'm currently feeling well, quarantined, and looking forward to rejoining my teammates when I am cleared," Westbrook said before thanking supporters for well wishes.
The Rockets are also without James Harden and assistant coach John Lucas, who did not travel with the team to Orlando last week.
It remains unclear what is keeping Harden and Lucas from the team.
Rockets head coach Mike D'Antoni told reporters Sunday evening he was expecting the players within the next few days.
Rockets forward Thabo Sefolosha is among the NBA players who decided not to participate in the league's restart.