Iran’s president insisted his country was not seeking a nuclear weapon as he acknowledged “great sorrow” after the authorities’ recent crackdown on protesters.

Speaking to crowds gathered across Iran to mark the anniversary of the 1979 revolution, Masoud Pezeshkian sought to claim a message of national unity after demonstrations that roiled the country and triggered an unprecedented crisis for the regime.

The comments were made against a backdrop of negotiations with the US that hang in the balance, with the prospect of a military confrontation on the table and repeated claims by Iranian military leadership that it is ready to confront and defeat America. On Tuesday, Donald Trump said he was considering sending a second aircraft carrier strike group to the Middle East to prepare for military action if talks with Tehran fail.

Pezeshkian said Iran was willing to negotiate over its nuclear programme and was “ready for any kind of verification” in relation to its insistence it is not trying to build nuclear weapons. However, the United Nations’ nuclear watchdog, the International Atomic Energy Agency, has been unable for months to inspect and verify Iran’s nuclear stockpile.

Pezeshkian said: “The high wall of mistrust that the United States and Europe have created through their past statements and actions does not allow these talks to reach a conclusion.

“At the same time, we are engaging with full determination in dialogue aimed at peace and stability in the region alongside our neighbouring countries.”

While he did not directly address the violent bloodshed by authorities in suppressing the protests, Pezeshkian said: “We are ashamed before the people. We are obliged to serve all those who were harmed in this process. We are ready to hear the voice of the people. We are servants of the people and we do not seek to confront the people.”

However, Pezeshkian spurned an appeal from leaders of reformist parties to speak out against the mass arrest of their leadership in recent days. In a statement the Reform Front told Pezeshkian that a failure to demand their release would be understood as a betrayal of his campaign promises and a blow to peace.

Lawyers acting for the detained reformists said they understood they were being kept in solitary confinement. Media organisations close to the security forces claimed the reforms were guilty of sedition by trying to organise a national conference to call for change.

The 1979 commemorations featured state television showing hundreds of thousands of people at pro-government rallies, which included the burning of American flags and cries of “death to America!” Yet the night before, witnesses heard shouts from people’s homes in the Iranian capital, Tehran, of “Death to the dictator!”

Alongside the crowds in the streets, pictures circulated of empty school desks adorned with red roses commemorating children killed in the protests. A teachers’ union said it believed on 213 children were killed.

Other regime figures used the anniversary of the revolution as an opportunity to reassert their ideological supremacy.

Brig gen Aziz Nasirzadeh, the defence minister, hailed the crowds as unique and claimed: “I have never seen such a passionate attendance in any year.”

He added: “They have participated in this march with full awareness, and this presence is more powerful than any bomb or missile.”

Away from the demonstrations, Iranian diplomats were trying to head off an attempt by Benjamin Netanyahu to toughen Trump’s negotiating stance with Iran before the Israeli leader’s meeting in the White House with Trump on Wednesday.

An Iranian foreign ministry spokesperson said the country was ready to discuss a reduction in the enrichment of uranium.

Israel wants the talks to include the question of Tehran’s ballistic missile programme, a matter that Iran has so far rejected. Tehran is determined that its stockpile of ballistic missiles, regarded as necessary for Iran’s defence, is excluded from the talks. Ali Shamkhani, a representative of the supreme leader, said the missile issue was not something that the negotiators had authority over.

In his latest remarks, Trump suggested Iran’s nuclear missiles would have to be included in any agreement

Ali Larijani, the secretary of Iran’s supreme national security council, visited Qatar after holding three hours of talks with mediators in Oman on Tuesday. Larijani is trying to craft a response to US demands that will keep within Iran’s red lines but still make the US believe talks are worth continuing.

Larijani kept open the possibility of wider talks with US, so long as next week’s talks are confined to guarantees about Iran’s civil nuclear programme.

Larijani said: “If the current negotiations with the United States are successful, they can be expanded and extended to other areas as well. However, at the moment, I cannot say definitively whether this path will lead to talks about other disputes with the United States or not.”