"For God's sake, this man cannot remain in power," Biden told a crowd in Warsaw.
Later a White House official clarified Biden was not calling for regime change in Russia when he said Putin "cannot remain in power".
"The President's point was that Putin cannot be allowed to exercise power over his neighbors or the region. He was not discussing Putin's power in Russia, or regime change," the official said following Biden's speech in Warsaw.
U.S. President Joe Biden also said that his country stood with Ukraine in its fight against Russia's invasion, in a fiery speech capping off a visit to Europe.
Biden's speech was delivered at Warsaw's Royal Castle before hundreds of Polish elected officials, students, and U.S. embassy staff, many holding the U.S., Polish and Ukrainian flags.
Biden said NATO was a defensive security alliance that never sought Russia's demise,
"The Kremlin wants to portray NATO enlargement as an imperial project, aimed at destabilizing Russia. Nothing is further from the truth. NATO is a defensive alliance, it has never sought the demise of Russia." Biden told a crowd.
He added that Ukrainians "are on the frontlines" in the fight for democratic principles.
"Now, in the perennial struggle for democracy and freedom, Ukraine and its people are on the frontlines, fighting to save their nation. And their brave resistance is part of a larger fight for the essential democratic principles that unite all free people."
He said the invasion was a strategic failure for Russia, but that it was nevertheless a challenge to the rules-based international order which threatened to return Europe to "decades of war".
After more than four weeks of fighting, Russia has failed to seize any major Ukrainian city.
The conflict has killed thousands of people, sent nearly 3.8 million abroad, and driven more than half of Ukraine's children from their homes
Intense fighting raged in several parts of Ukraine on Saturday, suggesting there will be no swift let-up in the month-old war.