In her interview with Israel's Channel 2, which was aired Thursday, Clinton said she found it "surprising how clear and compelling the case was where he quoted ISIS spokespeople rooting for Donald Trump because Trump has made Islam and Muslims part of his campaign."
During a new conference Thursday before she started a day of campaigning in North Carolina and Missouri, Clinton stood by the comment, saying that ISIS has "said that they hope (Trump) is the president because it would give even more motivation to every jihadi."
ISIS is "essentially throwing whatever support they have to Donald Trump," Clinton said.
Clinton has said in the past that ISIS is using Republican presidential nominee's comments to recruit new terrorists, but she has never directly said that the terrorist group is rooting for his candidacy.
Jason Miller, a Trump spokesman, said Clinton's comments were "unhinged and dishonest."
"These are the desperate attacks of a flailing campaign sinking in the polls, and characteristics of someone woefully unfit for the presidency of the United States," Miller added.
Matt Olsen, the former head of the National Counterterrorism Center, wrote in a piece for Time Magazine
that "ISIS has made clear that it's closely following this election, too -- and it has chosen a candidate." Olsen noted a number of public sources, including in August when one ISIS spokesman wrote, "I ask Allah to deliver America to Trump."
Clinton hit Trump on Thursday as "someone who has insulted Muslims, insulted a gold star family ... someone who has said he doesn't want to let Muslims from around the world come to our country."
Because of that, Clinton said, his presidency would be "a gift to ISIS."
The Clinton-Trump back and forth come as the 2016 presidential campaign focuses particularly on national security this week. Clinton has spent recent days knocking Trump's ability to serve as commander in chief, and the two candidates headlined an NBC veterans forum Wednesday.
Clinton's campaign is hoping to disqualify Trump with some military voters, aiming to cut into Trump's support among lean-Republican voters who prioritize national security.