Governments in France, Germany and Britain were still reviewing Iran's acceptance letter, while the United States, which has pushed for tougher U.N. action, waited on word from those countries before it gave its position on the deal.
"We will be talking to our friends and allies about this agreement," White House press secretary Scott McClellan said. "We will have more to say after we've had the opportunity to learn more about the specific details. At this point, we have not had that opportunity."
If the deal announced Sunday is accepted, Iran would escape U.N. Security Council sanctions and Europe might help Iran develop peaceful nuclear energy, the Associated Press reported.
While the U.N. nuclear watchdog supported the agreement, it said in a report summarizing its two-year investigation it could not completely rule out secret weapon development.
"All the declared nuclear material in Iran has been accounted for, and therefore such material is not diverted to prohibited activities," the International Atomic Energy Agency report said.
"The agency, is however, not in a position to conclude that there are no undeclared nuclear materials or activities in Iran," the report said.
Iran has said its nuclear program is focused on the peaceful purpose of generating electricity, Reuters reported.
The deal would commit Iran to suspending uranium enrichment as of Nov. 22, but Tehran could resume activities if negotiations fail.
Iran's chief negotiator, Hassan Rohani, said the country would not completely end its enrichment program, which purifies uranium for use as fuel, but he did not say how long the suspension would last.
IAEA's chief Mohamed ElBaradei said the agency had limited authority to investigate Iran's bomb-making and that further reports would only be issued "as appropriate."
The IAEA, however, did say it would continue to investigate traces of enriched uranium found in Iran. The traces had raised concerns that Tehran was enriching uranium for weapons. The agency added however they had no evidence to support this possibility.
The letter comes after talks in Paris last weekend with officials from France, Britain, Germany and the European Union, but the three countries are moving forward with caution.
The foreign ministries of the European countries had struck a deal 13 months ago with Iran, under which Iran agreed to suspend uranium enrichment and allow more aggressive inspections of nuclear facilities. Iran violated the agreement and the three countries conceded the deal had been made too quickly and the language in the final agreement was not clear enough.
The Bush administration has remained pessimistic about European negotiations with Tehran, but the president applauded the efforts at a joint press conference last Friday with British Prime Minister Tony Blair.
"We don't want Iran to have a nuclear weapon, and we're working toward that end," President Bush said. "And the truth of the matter is the prime minister gets a lot of credit for working with France and Germany to convince the Iranians to get rid of the processes that would enable them to develop a nuclear weapon."