Reuben Jeffery, under-secretary for economic, energy and agricultural affairs, made his appeal during a visit to the Turkmen capital Ashgabat on Sunday and Monday, the U.S. embassy said in a statement.
Jeffery "urged Turkmenistan to continue to work closely with multiple foreign governments and major international energy companies to develop Turkmenistan's energy sector, and offered the support and cooperation of the United States to achieve those goals," the embassy said.
Turkmenistan's vast natural gas fields have attracted the interest of Western energy majors. However, so far Turkmenistan favors Russia, which is the current top customer, and China, which is to be connected by an ambitious new export pipeline.
Jeffery, who is the U.S. State Department's top economics official, was meeting with Turkmenistan's President Gurbanguly Berdymukhamedov, among other officials.
Berdymukhamedov also serves as prime minister and head of parliament.
In office since the 2006 death of his dictatorial predecessor Saparmurat Niyazov, the Turkmen president has cautiously moved towards greater openness.