"Keep an eye on him, because he's not done," Clinton, the losing 2016 Democratic presidential candidate, said in an interview that aired Sunday on CNN's "Fareed Zakaria: GPS."
Clinton cited the intelligence community's assessment in January that Putin directly ordered
a Russian campaign to meddle in the 2016 presidential election to hurt Clinton and boost the Trump campaign.
She said Putin had gotten some of what he wanted in President Donald Trump, but that Russia is not getting as much as it otherwise could out of the US, due to the nation's system of checks and balances.
Clinton said she believed a grudge against her had motivated Putin, but that the Russian leader is also conducting a broader, ideological battle with the US.
"I think that Putin's campaign against us is much more about American democracy," Clinton said.
She said Putin hoped to increase polarization in the US.
"He wants an America that is divided from within," Clinton said.
Russia has repeatedly denied that it attempted to meddle in the 2016 US election, and Trump has wavered on the US intelligence community's conclusions.
In the interview recorded ahead of Trump's announcement on the Iran deal, Clinton criticized Trump for his expected decision to declare Iran not compliant with the deal and threaten to end it.
"I think it's very dangerous," Clinton said.
Trump made such claims in remarks
on Friday and pushed the issue to Congress.
Clinton said the moves sent "the wrong message" and undermined the credibility of the United States in the international community.
"It basically says America's word is not good," Clinton said.
Later in the interview, Clinton criticized Trump for the actions he has taken as President and the successful campaign he ran, which she said preyed on and stoked cultural anxiety in place of solutions that would help working people.
She said it was up to Democrats to stand up for people and explain that the working class is being misled by Trump and the GOP.
"We have to stand up for them," Clinton said. "And we have to do a better job, number one, of explaining to people 'you are being snookered.'"
Clinton pointed to public opinion polls showing relatively low approval ratings for the President as evidence the power of Trump's message was waning.
"His numbers are shrinking," Clinton said, adding many of those still with him are his diehard supporters.