Both were forced out of this week's US Open through injury but are in New York to fulfil television commitments, including Serena's appearance at Thursday's MTV Video Music Awards.
Despite rumours that fitness concerns and dwindling motivation may force them to re-think their careers, 23-year-old Venus told reporters: "I'm not going away.
"I'm not retiring before 33. I've thought about it already -- I'm not giving up my day job. I'm blessed and I love being out there."
Serena, the 21-year-old US Open champion, added: "I'm going to be a better player when I come back."
Serena, who has won five of the last six Grand Slam titles, withdrew from the hardcourt major after undergoing knee surgery earlier this month.
"My knee will be better than it's ever been in my career, which is really exciting, and I'm going to be mentally relaxed," she explained.
"I'm going to be stronger and I'm going to be angry."
But both former world number ones did not specify a date for their comebacks.
Four-times Grand Slam winner Venus, who withdrew from the Open last week, is still suffering from a stomach muscle strain that has troubled her since May. She is entered in the WTA Tour tournament in Moscow on September 29.
Serena's return may not be until the new season in January 2004, and she plans to take advantage of the free time by pursuing one of her other passions -- acting.
She has a part in an American television show called "Street Time", playing a reformed gang member who has been wrongly convicted of a felony.
"I love tennis," Serena said. "But in a way it's a relief to see that this actually gives me a chance to do some other stuff, especially acting."
Their absence from the US Open has been welcomed by those who complain their dominance has ruined the women's game, and bemoaned by those who argue it has detracted from the competition at Flushing Meadows.
"You can't win either way with us," said Serena.
"Without us, there is a lot left...but I think Venus and I bring a huge aspect to tennis.
"Without us, it is a little dry. I would be dishonest if I said it wasn't."
