GENEVA — Iranian and American officials ended a round of high-level nuclear talks here on Monday considering a proposal that would strictly limit, for at least 10 years, Iran’s ability to produce nuclear material, but gradually ease restrictions on Tehran in the final years of any deal.

The proposed phasing out of restrictions is part of a broader effort to mollify critics in Tehran, where some hard-liners in the government and the military oppose any deal that would force Iran to forsake nuclear production for a generation, and Washington, where some members of Congress have objected to an agreement that would not impose lengthy restrictions on Iran’s program.

The question of how long any agreement would endure is a critical one: President Obama and Secretary of State John Kerry have said they will not sign an agreement that would give Iran the ability to produce enough fuel for a nuclear weapon in less than a year should it decide to “break out” of the accord. But it is also an issue that has sharply divided the two sides. While the United States has long insisted that an agreement to limit Iran’s nuclear program endure for a prolonged period, which could be 15 years or more, some Iranian officials have argued that an agreement allow their country to ramp up the number of centrifuges to enrich uranium in seven years or less.

Easing limits on Iran’s production during the later years of an accord would be an attempt to bridge the differences between the two sides over how long an agreement should last. If strict constraints on the number of centrifuges were maintained for the first 10 years of a potential 15-year agreement, for example, that would allow the Iranians to say the tough constraints would last for only 10 years and the Americans to say they had a 15-year agreement.