Mark C. Toner, a spokesman for the State Department, said in an email message late Wednesday, “We have seen reports in the media, but at this time have received no official offer of assistance from the Iranian government or any Iranian entity.”

Dealing regularly with floods and earthquakes, Iran’s Red Crescent Organization is experienced in providing immediate assistance following disasters. But the organization, the Islamic version of the Red Cross, is closely affiliated with Iran’s government. According to documents disclosed by WikiLeaks, American officials suspect that some Red Crescent employees operate as spies when providing help in other countries.

The United States and Iran have not had diplomatic relations since the aftermath of the 1979 hostage taking of the United States Embassy in Tehran, but natural disasters have sometimes been a way of engaging in direct communication, beyond politics.

In 2003, the United States sent a C-130 military transport plane with a rescue team and an ambulance to the southeast Iranian city of Bam where 25,000 people died in a devastating earthquake, and in August the United States offered to do the same when more than 300 people were killed in two deadly earthquakes in the northwestern part of the country.

While Iranian authorities turned down the most recent offer, the United States Treasury Department temporarily lifted sanction restrictions to allow charities to send goods and money to the stricken area.