"The North Koreans should notify the world of their intentions, what they have on top of that vehicle and, you know, what are their intentions," said Mr Bush.
"We have not heard from the North Koreans, so I can't tell you what their intentions are," he said. "That's part of the problem."
White House spokesman Tony Snow has rejected calls from some senior US lawmakers to hold direct talks with Pyongyang outside the stalled six-country negotiations on North Korea’s nuclear weapons programs.
Mr Snow said there was no point in rewarding bad behaviour.
US and Asian officials have said North Korea is preparing to launch a
Taepodong-2 missile, which could potentially hit Alaska or possibly Hawaii.
The possible missile test firing comes amid a standoff over North Korea’s nuclear program.
North Korea fired a Nodong missile in 1993 and five years later launched a Taepodong-1 over Japan into the Pacific Ocean.
"I have made clear to our partners on this issue -- that would be Japan and South Korea and China and Russia -- that we need to send a focused message to the North Koreans and that this launch, you know, is provocative," said Mr Bush.
"And I was pleased to hear that the Chinese have delivered that message to the North Koreans. And we would hope that the leader in North Korea listen to the Chinese," said the US president.