ISTANBUL — Iranian President-elect Ebrahim Raisi said Monday that he opposes talks on limiting Tehran’s ballistic missile program and its support for regional proxy forces.

Speaking in the Iranian capital at his first news conference since winning Friday’s presidential election, Raisi also said he is not willing to meet President Biden, even as the two sides work to revive a 2015 nuclear deal between Iran and world powers.

When asked by a reporter whether he was willing to meet Biden, Raisi simply said, “No.” He added that Iran’s ballistic missiles and regional presence are “not negotiable.”

He made the comments a day after Iranian authorities said they had temporarily shut down the country’s only nuclear power plant because of unspecified technical difficulties. A statement from the Atomic Energy Organization of Iran late Sunday said the Bushehr plant on the Persian Gulf was shut down following a “technical defect” and would be disconnected from the national power grid for several days.

Raisi, an ultraconservative Shiite cleric, is a hard-liner who had the backing of Iran’s supreme leader, Ayatollah Ali Khamenei, and allied security services in the election. His victory marks a shift from the more reform-minded presidency of Hassan Rouhani, a moderate pragmatist who favored engagement with the West.

Human rights groups have linked Raisi, who most recently served as chief of Iran’s judiciary, to numerous episodes of repression over decades and said he played a central role in mass killings of dissidents in the late 1980s. Raisi had “been a member of the ‘death commission’ which forcibly disappeared and extrajudicially executed in secret thousands of political dissidents in Evin and Gohardasht prisons near Tehran in 1988,” Amnesty International said in a statement Saturday, calling for Raisi to be investigated under international law.

Asked about the allegations Monday, Raisi said, “I have always defended people’s rights since the beginning of my responsibilities. Human rights have been a pivotal point for me.”

He faces political, economic and diplomatic challenges as Iran continues to grapple with the effects of U.S. sanctions. Iran and world powers are working to resolve major issues that stand in the way of the United States returning to the landmark accord, from which the Trump administration withdrew in 2018.

Raisi’s election was not expected to affect ongoing negotiations in Vienna to revive the accord, in large part because Khamenei has allowed Iran to reopen the dialogue and appears ready to keep it going in efforts to get the international sanctions lifted.

State Department spokesman Ned Price said Monday that U.S. officials’ indirect talks with their Iranian counterparts would continue in Vienna, with the goal of restoring mutual compliance on the nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA). He said the Biden administration’s objective of preventing Tehran from obtaining a nuclear weapon had not changed and that Iran’s supreme leader, not its president, remains responsible for major decisions.

“Our Iran policy is designed to advance U.S. interests. That is regardless of who is chosen Iran’s president in a process that we consider to be pre-manufactured,” Price said of the election.

Price, speaking in a phone briefing with reporters, said the seventh round of discussions would take place “in coming days.”

Asked about Raisi’s suggestion that Iran would not permit its ballistic missile program and its support for external proxy forces to be subject to international negotiation, Price said the United States would seek to address those issues through “follow-on diplomacy” after any restoration of the nuclear deal.

“We are confident that, if we are able to return to JCPOA compliance, from there we have the additional tools we need to address the issues outside of the nuclear deal,” he said. “In fact, we’ll be better positioned than we are right now.”

European diplomats said Sunday that no deal had been struck at the conclusion of the sixth round of negotiations.

“We continue to make progress and have managed to agree on a number of important elements, but we still need to resolve the most difficult issues,” said a statement from senior European diplomats involved in the negotiations.

“Time is on nobody’s side. These talks cannot be open-ended,” the statement said. “The time for decision is fast approaching.”

The emergency stoppage at Bushehr, which one official said could cause power outages, follows mysterious explosions and blackouts at key Iranian nuclear facilities over the past year, including one in April that crippled the power grid at a critical uranium-enrichment site at Natanz.

Iran blamed that incident on Israel, with a Foreign Ministry spokesman denouncing it as “nuclear terrorism.”

Iran already is beset by frequent blackouts that the government has blamed on illegal bitcoin mining. In March, a senior official at the Atomic Energy Organization said that U.S. sanctions were hurting Iran’s ability to obtain parts from Russia for the Bushehr plant and that it could shut down as a result.

The reactor in the southern port city of Bushehr is still monitored by the International Atomic Energy Agency and is powered by uranium produced in Russia, which helped complete the plant’s construction in 2011.

Work on the plant started in 1975, led by a German company, as part of the shah of Iran’s ambitious nuclear power program, and it was nearly complete when the shah was overthrown in the 1979 Islamic revolution. The new revolutionary government immediately stopped construction, and Iran was soon plunged into a nearly eight-year war with neighboring Iraq, whose forces repeatedly targeted the facility.

Fahim reported from Washington. Loveday Morris in Berlin and Missy Ryan in Washington contributed to this report.