The US and the other countries negotiating with Iran are concerned Tehran is secretly using its nuclear programme as a cover to develop atomic weapons, a charge Iran denies.
The group, which includes China, Russia, France, Britain and Germany, has offered to take Iran's low-enriched uranium and process it abroad into fuel for a civilian reactor, but Iran has not agreed to the plan.
Speaking at a news conference after the meeting with Obama, Erdogan said Turkey was ready to do whatever it could to achieve a diplomatic solution on the nuclear issue, adding that its good contacts and ties with Iran could prove useful.
"As long as Iran is willing to increase its nuclear capability for civilian purposes or peaceful purposes, we will never have a negative approach towards this demand," he said.
"We do not want to see a country in our region possessing nuclear weapons and we want the countries in our region who have nuclear weapons to be rid of them."
Erdogan previously raised concerns in Washington in October when he accused the West of treating Iran unfairly by demanding that it halt its nuclear programmes, while not demanding the same of nuclear armed countries in the region, an allusion to Israel.
Last week Erdogan took issue with a vote by the International Atomic Energy Agency (IAEA), the UN's nuclear watchdog, to censure Iran after Mahmoud Ahmadinejad, the Iranian president, rejected a Western offer to enrich uranium outside Iran to fuel a research reactor.
Ahmadinejad responded to the IAEA vote by threatening to build 10 more uranium enrichment facilities, in addition to two existing facilities, so that it can enrich uranium on its own.
Obama also praised Turkey for its role in Afghanistan on Monday.
Erdogan said Turkey could train Afghan soldiers and police but gave no indication of providing combat troops to the Nato-led force there.
Turkey currently has 1,700 troops in Afghanistan serving in non-combat roles.