The two have been married for five years and have a 4-year-old daughter, Sasha, said Fox's spokeswoman Staci Wolfe.
"They are both extremely devoted parents, so the most important thing to them right now is the welfare of their child," Wolfe said. "They are committed to working out what's best for her."
Wolfe declined further comment.
Fox, who played with the Lakers (search) for seven years, was traded last week to the Boston Celtics. The 35-year-old may retire because of nagging injuries rather than play in Boston, according to Celtics director of basketball operations Danny Ainge.
Fox has dabbled in acting, appearing in movies including "Holes" as well as TV series such as HBO's "Oz" (search) and Lifetime's "1-800-Missing."
Williams' publicist Brad Cafarelli declined comment.
Williams' film credits include 2000's "Shaft," 1997's "Soul Food" and this year's "Johnson Family Vacation." The 41-year-old has also appeared in Broadway musicals including "Into The Woods." She won the Miss America (search) pageant in 1984.
Williams has three children from her first marriage, and Fox has a son from a previous relationship. The two had been separated.