Gordon Johndroe, a spokesman, said: "President Bush reiterated the importance of continuing to apply pressure through the United Nations to insist on verifiable Iranian suspension of its nuclear enrichment activities."
Russia is helping Iran build its first nuclear power plant in Bushehr meant for civilian consumption, but Western nations say it is a guise to build atomic bombs, claims Tehran has denied.
Bush, who insists on a diplomatic solution, has not ruled out military action if all else fails.
He said he would ask Putin to clarify his remarks on Iran's nuclear activities.
During the Iran trip, Putin had made it clear that Moscow would not accept any military action against the Islamic republic.
He said while Russia held that Tehran was not developing nuclear weapons he did share concerns that its programmes be open to international scrutiny.
Bush is pushing for a third round of UN sanctions against Iran.
Russia, a veto-holding member of the Security Council, backed two sets of limited UN sanctions against Iran but has resisted any tough new measures.