Williams won her 23rd Major title while pregnant at the 2017 Australian Open but has not claimed any event since.
And the American superstar, who lost the finals at Wimbledon and the US Open last year, remains one behind the mark set by Margaret Court.
John McEnroe warned this week that Williams, who turns 38 in September, only has a maximum of two years to win a record-equalling title.
And King said: “She does have her finger in so many pies – she’s got business, a baby, she’s trying to help gender equality, particularly for women of colour.
“But all that makes it much harder to commit to winning a Grand Slam. I would like to see her put everything else aside from that. She’s got people working on these things.
“I wish she would just make a commitment for the next year-and-a-half to two years and just say: ‘I’m going to absolutely devote what’s necessary for my tennis so when I look in the mirror when I’m older that I can go back in my mind and know I gave everything I had and be happy’.
“But if she’s happy doing it this way it’s fine.”
World No.11 Williams has won only nine matches in five events in her injury-hit season – and decided not to play a grass-court warm-up event after losing in the third round of the French Open.
King added: “Ideally I would like her to play more matches before she gets to Wimbledon.
“In the old days they could kind of get through and then get going by the second week but I think when you’re older, it doesn’t work that way. The women’s event is wide open.”
King said she hoped Williams would play in the revamped Fed Cup next year which will be staged in Budapest in April.
Promoted as the “World Cup of Tennis”, 12 teams will compete over six days on clay for US$12m (£9.33m) in prize money.
Anne Keothavong’s Great Britain team will have the chance to qualify through home-and-away playoffs in February.
Fed Cup Global Ambassador King said: “I have been watching the women’s World Cup and that is what I want for us. There is a new wave in women’s sport – there is definitely a women’s sports movement.
“Team sports are continuing to grow and mega-events like this are absolutely vital.”
The Davis Cup finals, which have undergone a similar change, will be held in Madrid in November.
