Nastase also ran afoul on Saturday as the Romanian Fed Cup captain was ejected from the World Group II playoff against Great Britain after verbally abusing members of the opposing team.
According to multiple reports, Nastase shouted profane comments at Johanna Konta, her coach and the umpire during the second set of the match in Constanta, Romania. The 70-year-old Nastase, who had received two official warnings before finally getting tossed, initially took a seat in the stands before being escorted to the locker room and then ultimately removed from the stadium grounds.
Nastase's actions on Saturday came one day after he directed racially insensitive comments toward Williams in regard to her unborn baby.
"Let's see what color it has. Chocolate with milk?" Nastase was overheard to say in Romanian in regard to the 23-time grand slam singles champion.
Williams announced Wednesday that she is expecting her first child with fiance Alexis Ohanian, who is white.
The International Tennis Federation offered a statement of its own.
"The ITF does not tolerate discriminatory and offensive language and behavior of any kind," the tennis governing body's statement read. "We are aware of alleged comments made by Romanian captain Ilie Nastase and have begun an immediate investigation so that we have the full facts of the situation before taking further and appropriate action."
Nastase also made unsubstantiated allegations last month of doping by Williams based on her physique.