(CNN) -- An event to remember the victims of Iran's post-election protests has been postponed Thursday, a day after security forces crushed a planned demonstration.
The postponement was announced on the Web site of presidential candidate Mehdi Karrubi's party Wednesday evening.
"Thursday's ceremony was meant to commemorate the 'the martyrs of the republic and freedom,' " the statement on the party site said.
The event was postponed for a week, but the site did not offer an alternate date.
Also Thursday, Mahmoud Ahmadinejad, the declared winner in the disputed June 12 election, told President Obama to stop "interfering" in Iran's affairs, the semi-official Fars news agency reported.
"The question is, do you want to use this kind of literature to address Iran and create a dialogue?" Ahmadinejad said. "If this is your position, then there is nothing to talk about."
Obama is walking a diplomatic tightrope in finding the right response to the crisis. Since taking office, the U.S. leader has sought rapprochement with Iran, but this week he said he was "appalled and outraged" by the post-election violence.
The White House said Wednesday that it was rescinding invitations to Iranian diplomats overseas for Independence Day celebrations.
Seventeen people have died in clashes with government forces since the protests began more than a week ago, according to official figures.
CNN has received unconfirmed reports of as many as 150 deaths related to a popular uprising on Saturday alone.
The mood in Tehran on Thursday was "defiant but nervous," said one resident, whom CNN is not identifying for safety reasons.
Life was returning to routine, "but not like before the election," the resident wrote. Security forces were ever-present, he said. And after days of protest, the city was calmer.
The number of demonstrators venturing into Tehran's streets had fallen since Sunday, said CNN's Reza Sayah, who returned Wednesday to the U.S. from Iran.
Sayah said exhaustion from consecutive days of protest may have combined with fear of government reprisals.
CNN has received numerous accounts of nighttime roundups of opposition activists and international journalists by government forces.
After opposition leader Mir Hossein Moussavi met with university teachers Wednesday, police arrested 70 attendees and took them to an undisclosed location, his Web site said. CNN hasn't been able to verify the site's authenticity.
The key to what happens next depends on what role Moussavi plays, Sayah said. Moussavi's supporters say he was robbed of a victory and are demanding a fresh election. The official results gave Ahmadinejad a landslide win.
Meanwhile, Iran's ambassador to Mexico defended his country's actions in an interview Wednesday with CNN en Español. Ambassador Mohammad Hassan Ghadiri said there are acceptable ways of addressing electoral fraud, if any had occurred.
"But they go out on the street, they attack buses, they attack banks; that affects the security of the country," Ghadiri said.
"The minority can't impose their opinion on the majority. They can't impose a dictatorship, saying that the majority is not going to govern."
In the face of protests, authorities offered a partial recount. The Iranian Interior Ministry said Wednesday that it conducted a recount of some ballot boxes in the presence of another defeated candidate's representatives -- and found no discrepancies. VideoWatch more on the protests »
Iran's government has restricted media access in the country, making it difficult to ascertain exact figures.
On Wednesday afternoon, security forces used overwhelming force to crack down on protesters who had flocked to Baharestan Square near the parliament building in Tehran, according to more than a half-dozen witnesses.
Police charged at the gathering -- clubbing demonstrators with batons, beating women and old men, and firing weapons into the air to disperse them, witnesses said. VideoWatch what Iranian television is reporting »
"They were waiting for us," one witness said. "They all have guns and riot uniforms. It was like a mouse trap."
The melee extended beyond the square, one woman said.
"They emptied buses that were taking people there and let the private cars go on ... and then, all of a sudden, some 500 people with clubs of wood, they came out of the Hedayat Mosque, and they poured into the streets and they started beating everyone," she said.
Government-run Press TV gave a starkly different account, saying about 200 protesters had gathered in front of the parliament and 50 others in a nearby square. All were dispersed by a heavy police presence, it said.
Someone who answered the phone at the nearby Bank of Melli hospital said no one had been admitted as a result of any clashes.
Iran's supreme leader, Ayatollah Ali Khamenei, who has endorsed the election results, reiterated Wednesday that the government "will never give in to coercive demands with regards to Iran's presidential elections," Press TV said.
Also Wednesday, Iranian authorities said they had arrested foreign nationals, some with British passports, in connection with the country's post-election unrest. VideoWatch more on the diplomatic standoff »
The British Foreign Office said it was looking into the claims. It said it knew that one of the arrested nationals was Washington Times reporter Jason Fowden, who also goes by the name Iason Athanasiadis.
The Iranian government has long blamed other countries, especially Britain, for meddling in its affairs but has offered no proof.
Iran also said that Neda Agha-Soltan, 26, whose videotaped death has made her a face of the protests, might have been shot by mistake.
The state-run Islamic Republic News Agency said snipers may have mistaken her for the sister of a Monafeghin.
Monafeghin refers to the People's Mujahedin Organization of Iran, which promotes a Marxist government and has waged a campaign against the fundamentalist Islamic regime.