Afghanistan is Nato's biggest challenge, Hillary Clinton says
Iran would consider a US invitation to a conference on Afghanistan later this month, a government spokesman has said.
Tehran declared that it was ready to review any approach from Western powers, as it would offer any help to its eastern neighbour.
US Secretary of State Hillary Clinton said in Brussels this week Iran should be included in the Afghanistan summit.
President Obama has said the United States is ready to talk to Iran if it "unclenched its fist".
Iranian government spokesman Gholamhossein Elham said: "If America and European countries and others need to use Iran, they should give us [the invitation]."
Nato's 'biggest challenge'
"We will review it with the approach that we are ready to offer any help to Afghanistan," he told a news conference on Saturday, reported Reuters news agency.
Mrs Clinton, who visited Turkey on Saturday, has proposed the conference for 31 March, at a location to be decided. It aims to bring in Afghanistan's other neighbours, such as Pakistan.
She said on Thursday: "There are a lot of reasons why Iran would be interested. So they will be invited. Obviously it is up to them to decide whether to come."
She called Afghanistan "Nato's biggest military challenge".
French Foreign Minister Bernard Kouchner said he hoped Iran would attend such a meeting, but noted Tehran had failed to attend recent French talks on Afghanistan.
The US is at odds with Iran over its nuclear programme, which Washington says is aimed at building an atomic bomb. Tehran says it is a civilian energy programme.
Iran, which opposed the Taleban regime toppled by the US-led invasion of Afghanistan in late 2001, has experienced a rise in drug use as easily available heroin from Afghan opium harvests flows across the border.