The former senior adviser to George W. Bush told The Daily Telegraph of London that he questioned whether Americans thought the former Alaska governor had the "gravitas" for the "most demanding job in the world."
It was a stronger stand than Rove took earlier in the week in addressing Palin's prospects for 2012.
Rove previously also spoke out about Republican Senate candidate Christine O'Donnell in Delaware, saying she couldn't win the general election, but he later backpedaled on the statement.
Noting Palin's upcoming TV series on Alaska wilderness, Rove told the Telegraph it was unlikely that voters would regard someone starring in a reality show as presidential material.
"With all due candor, appearing on your own reality show on the Discovery Channel, I am not certain how that fits in the American calculus of 'that helps me see you in the Oval Office,'" Rove told the Telegraph, which said he remains a considerable force on the U.S. political scene.
Rove cited the promotional clip for "Sarah Palin's Alaska," saying it could be especially detrimental to any political campaign as it features the mother of five in the great outdoors saying "I would rather be doing this than in some stuffy old political office," the Telegraph reported.
The newspaper said Rove also implied that the former vice presidential candidate lacked the stomach for the rigors of a presidential primary campaign.
He said it's too early to tell if Palin, 46, would be the wisest choice among the candidates for the party to seize the White House from President Obama in 2012.
The Telegraph quoted Rove: "You can make a plausible case for any of them on paper, but it is not going to be paper in 2011. It's going to be blood, it's going to be sweat and tears, and it's going to be hard effort."
That remark echoed comments Rove made on CBS' "Face the Nation" Sunday:
"Every one of these prospective candidates, if they decide to enter the race, has strengths that they need to work on magnifying and weaknesses that they need to endeavor to overcome — or challenges that they need to overcome. And we don't know how that's going to play out," Rove said.
But he wouldn't comment Sunday on Palin's potential strength.
"I don't know if she runs or not and if she would be a formidable candidate. But, look, there are going to be several geological ages that are going to come and go before the 2012 Republican presidential nomination fight gels," Rove said.
On Wednesday, the Telegraph said Rove praised Palin for doing a "terrific job" in 2008 as John McCain's running mate, but, "Being the vice-presidential nominee on the ticket is different from saying 'I want to be the person at the top of the ticket.'
"There are high standards that the American people have for it [the presidency] and they require a certain level of gravitas, and they want to look at the candidate and say 'that candidate is doing things that gives me confidence that they are up to the most demanding job in the world'."