Foreign ministers from the Group of Eight leading industrial nations will call on the international community to take "appropriate and strong steps" to show its resolve over Iran's nuclear activities.
A draft of the final communiqué also said the G8 remained open to dialogue with Tehran, which denies widespread western charges that it is seeking to make atomic weapons.
The G8 ministers will end a two-day meeting in Canada today.
The document is the latest step in a campaign of pressure by many of the world's most powerful nations to force Iran to comply with demands from the UN Security Council and cooperate with the International Atomic Energy Agency.
Iran insists its nuclear program is for peaceful purposes.
"Iran's continued noncompliance with its United Nations Security Council and IAEA obligations regarding its nuclear program is of serious concern to G8 ministers," said the final communiqué.
"Ministers agreed to remain open to dialogue and also reaffirmed the need for the international community to take appropriate and strong steps to demonstrate ... resolve to uphold the international nuclear non-proliferation regime."
The draft did not mention the word "sanctions".
The three Western members of the Security Council - the United States, France and Britain - along with Germany have been pushing hard for a new round of sanctions against Iran.
Russia has been less enthusiastic but has recently signalled it may come on board. But China, which enjoys close economic links to Iran, has repeatedly said that the world needs more time to find a diplomatic solution to the standoff.
Earlier, US secretary of state Hillary Clinton played down fears China was out of step with the other permanent members of the Security Council on the question of imposing more sanctions.
Reuters