Updated

President Barack Obama urged China's leader in a phone call Monday to send Beijing ally North Korea a message that "its provocations are unacceptable," while the Chinese leader urged restraint.

Chinese President Hu Jintao said during the conversation that China was "greatly concerned" about the current tension on the peninsula and called for "calm and rational response" from all sides, China's official Xinhua News Agency said.

"The fragile security situation on the Korean Peninsula, if not properly handled, could lead to further escalation of tension, or even run out of control, which is not in the common interests of all parties concerned," Xinhua quoted Hu as saying.

In Washington, the White House said the leaders talked about their common interest in peace and stability in Asia and the importance of keeping the Korean peninsula free of nuclear weapons.

Obama condemned North Korea's pursuit of a uranium enrichment program as well as the shelling of the South Korean island in which four people were killed, it said.

Obama "urged China to work with us and others to send a clear message to North Korea that its provocations are unacceptable," a White House statement added.

China is North Korea's most important ally and has been pressured by the U.S. and others to use its influence to rein in Pyongyang following its shelling of the South Korean island on Nov. 23.

Beijing has been reluctant to take forceful action that risks angering or destabilizing the Pyongyang regime, preferring to call for a resumption of six-nation North Korean nuclear disarmament talks.