Syria has threatened to close its border with Lebanon if the United Nations deploys peacekeepers in the area.
Finland's foreign minister Erkki Tuomioja says the threat came during a meeting Wednesday with Syrian Foreign Minister Walid Mualem.
Finland is the current president of the European Union, which is struggling with committing troops to the U.N. peacekeeping force.
A White House spokeswoman Dana Perino says the United States is not taking Syria's threat seriously. She said Syria is not a party to talks on deploying peacekeepers in Lebanon and that if the Syrian president was not supplying Hezbollah, there would be no problem.
The U.N. Security Council approved boosting its Lebanese peacekeeping force by another 15,000 troops as part of the ceasefire between Israel and Hezbollah.
Several European countries have said they are reluctant to commit ground troops unless the rules of engagement are clear and peacekeepers can defend themselves.
Also Wednesday, Lebanese Prime Minister Fuad Siniora called on the United States to pressure Israel to lift its blockade of Lebanon. Israel says it will end the blockade when international peacekeepers are in place.
Information for this report is provided by AP, AFP and Reuters.