President Bush and German Chancellor Gerhard Schroeder vowed yesterday to take a firm stance with the newly elected government of Iran over the country's nuclear development program, foreshadowing a fresh season of discord with an increasingly defiant Tehran.

Bush and Schroeder, whose bitter split over the war in Iraq left their relationship strained, presented a common front on Iran during an Oval Office meeting just days after the surprise victory of Tehran's hard-line mayor, Mahmoud Ahmadinejad, as the next president. Ahmadinejad, a former Revolutionary Guard officer, has strongly defended Iran's right to develop nuclear power for civilian purposes and scorned diplomatic rapprochement with the United States.

"My message . . . is that we continue working with Great Britain, France and Germany to send a focused, concerted, unified message that says the development of a nuclear weapon is unacceptable," Bush said. "And a process which would enable Iran to develop a nuclear weapon is unacceptable."

Schroeder seconded the sentiment: "I couldn't agree more with this message. We are going to continue being tough and firm on all of that." At the same time, he signaled optimism that negotiations could still yield a compromise. "The new president has emphasized that he wants the talks to continue," the German leader said.

Bush, who has accused Iran of secretly developing nuclear weapons under the cloak of a civilian energy program, has backed a European initiative led by Schroeder and his British and French counterparts to negotiate an accord with Tehran, which denies having a clandestine weapons program and resents the outside pressure. The Bush team remains skeptical that the European approach will work but views it as a means of keeping together a coalition that could pursue tougher measures if talks fail.

Ahmadinejad softened his rhetoric Sunday, promising "a policy of moderation" and agreeing to leave nuclear talks with Europe in the hands of the negotiating team. But he maintained that Iran's nuclear ambitions extend only to civilian uses and refused to abandon them.

During his appearance with Schroeder, Bush repeated his criticism of the Iranian election as an exercise manipulated by the country's ruling clerics. "It's never free and fair when a group of people, unelected people, get to decide who's on the ballot," he said.

For Schroeder, the visit came at a sensitive moment when elections in his economically ailing country threaten to end his political career. The German leader asked parliament yesterday to hold a vote of confidence in his government, a key step in his plan to call early national elections. In a gesture to Schroeder, Bush called him "a friend" and declined to rule out a permanent seat on the U.N. Security Council for Germany, a cherished goal of the chancellor. "We oppose no country's bid for the Security Council," Bush said.

Yet Bush offered only tempered words when asked if he had wished Schroeder luck in the elections. "He's a seasoned political campaigner, and if there's elections, I'm confident he knows what he's going to do," Bush said. He added: "As we say in Texas, this won't be his first rodeo."

And Bush's statement on a Security Council seat for Germany seemed in conflict with the administration's private position. According to a confidential memo, Secretary of State Condoleezza Rice told a congressional task force last month that she "thought that there was a very poor rationale for giving another member of the European Union a permanent seat."

President Bush and German Chancellor Gerhard Schroeder talk to reporters about Iran. They pledged firmness in dealing with the nuclear plans of the new leadership there.