"If the administration believes that any, any use of force against Iran is necessary, the president must come to Congress to seek that authority," Clinton said in a Senate speech.
Clinton, a member of the Armed Services Committee, voted in 2002 to give Bush the authority to use military force in Iraq — a vote that has prompted some Democrats to demand that she repudiate.
Since then, the New York senator has become an outspoken critic of Bush's handling of the war. She said the new Democratic Congress must not let him make similar mistakes in the increasingly tense relationship with Iran.
"It would be a mistake of historical proportion if the administration thought that the 2002 resolution authorizing force against Iraq was a blank check for the use of force against Iran without further congressional authorization," Clinton said.
She also insisted the resolution authorizing force against those responsible for the Sept. 11, 2001 terrorist attacks did not allow for U.S. action now against Iran.
Clinton, who has come under fire from anti-war Democrats, excoriated the previous Republican-controlled Congress for not questioning the administration over the past six years.
"We continue to experience the consequences of unchecked presidential action," she said, later adding: "This president was allowed for too long to commit blunder after blunder under cover of darkness provided by an allied Republican Congress."
Clinton spoke shortly after Bush said he was certain the Iranian government is supplying deadly weapons used by fighters in Iraq against U.S. troops, even if he can't prove that the orders came from top Iranian leaders.
"I'm going to do something about it," Bush pledged, displaying apparent irritation at being repeatedly asked about mixed administration signals on who was behind the weaponry.
U.S. officials have said that Iran is behind attacks against troops in Iraq, an assertion denied by Iran's president, Mahmoud Ahmadinejad.