Turkey indicated that it will only enforce sanctions that have been approved by the United Nations, and its announcement is a setback to US sanctions aimed at halting what Western governments say is Iran's effort to develop nuclear weapons.
Those penalties, targeting Iran's oil industry, would bar financial institutions from the US market if they do business with Iran's central bank.
US Treasury Secretary Timothy Geithner on Thursday secured the support of Japan which pledged to buy less Iranian oil, a day after China reacted coolly to the US effort.
Japan imports about 10 percent of its oil from Iran, while Turkey imports about 30 percent from Iran.
"Turkey does not feel it is bound by any sanctions taken unilaterally or as a group, other than those imposed by the United Nations," Turkish Foreign Ministry spokesman Selçuk Ünal told a news conference, which followed a meeting between Foreign Minister Ahmet Davutoğlu and Iran's parliamentary speaker, Ali Larijani.
US Deputy Secretary of State William Burns, who visited Turkey earlier this week, said the United States and Turkey share a broad strategic concern about the possibility of Iran developing a nuclear weapon.
"I think both of our countries agree strongly that this would be a very dangerous and destabilizing development for the entire region," Burns told Turkey's state-run Anatolia news agency. "While it is true we sometimes differ over tactics, I think we share that strategic concern, which is very important."
Ankara has agreed to host NATO's early warning radar as part of NATO's missile defense system, which is capable of countering ballistic missile threats from Iran. Turkey insists the shield doesn't target a specific country, but Tehran says the radar is meant to protect Israel from Iranian missile attacks if a war breaks out with the United States and or Israel.
The Jewish state, which views Tehran as a threat, has warned of a possible strike on Iran's nuclear program. Iran, which insists its nuclear program is for peaceful purposes, has threatened to respond to sanctions by shutting the Strait of Hormuz, a transit route for a fifth of the world's oil.
China has criticized US sanctions against Iran, approved by President Barack Obama on New Year's Eve, as improper and ineffective. Beijing supported UN sanctions on Iran's nuclear program, but says such action should be multilateral. China, the world's biggest energy consumer, depends on Iran for 11 percent of its oil imports.
Turkey said it would evaluate the content of the US sanctions, but Turkey's biggest crude oil importer Tüpraş already has renewed a contract to continue to import crude oil from Iran in 2012.
"Right now, our import is continuing and as of today there is no change to our plans," Energy Minister Taner Yıldız said on Thursday.
Larijani, after meeting his Turkish counterpart Cemil Çiçek, said there were vast opportunities to increase bilateral cooperation in several fields, including natural gas and oil, to increase the bilateral trade volume of US$15 billion (11.7 billion euros).
"There are those who want to trouble the relations between the two countries," said Çiçek without elaborating. "We should not allow them."
Davutoğlu, who visited Tehran last week, said Turkey is ready to host further talks with world powers and Iran over its nuclear program.