The missile, named Babur or Hatf VII, has a range of 434 miles and is capable of carrying various types of warheads, including nuclear, the military-run Inter-Services Public Relations Directorate said.
"The test is part of Pakistan's ongoing efforts at consolidating its strategic capability and strengthening national security," the directorate said in a statement.
Babur was first tested in 2005. It was test-launched again Thursday with an enhanced range, a military official said.
"Babur was tested successfully with new technical parameters and enhanced edge," said Maj. Gen. Waheed Arshad, the top army spokesman.
Neither Arshad nor the military statement specified site of the missile launch.
President General Pervez Musharraf and Prime Minister Shaukat Aziz congratulated the scientists and engineers for "this very important success" of the test, the military statement said.
Pakistan routinely tests various nuclear-capable missiles in its arsenal, believed to be designed mainly to match that of neighboring archrival India.
The two countries have a history of hostile relations. Both carried out underground nuclear tests in May 1998.
However, in 2004 they began a series of negotiations to normalize relations and settle their dispute over the Himalayan territory of Kashmir, the main cause of bitterness between them.
Pakistan and India have fought two wars over Kashmir since their independence from British rule in 1947. Kashmir is split between the two countries, but each claims the whole of it.
India and Pakistan have an agreement under which each country informs that other ahead of its missile tests.
But Pakistan did not inform India of the test Thursday because the accord does not include providing prior information on cruise missile tests, a military official said on condition of anonymity because he was not authorized to comment to media.
In February, Pakistan successfully test-fired a new version of its long-range nuclear-capable missile, Hatf VI (Shaheen II), which has a range of 1,245 miles.