The Internet warning follows the death on Wednesday of al-Qaeda in Iraq's leader Abu Musab al-Zarqawi in a US air strike.
"This is a propaganda ploy," Iraq's national security adviser Mowaffak al-Rubaie said, speaking to CNN.
"They're trying to make up for the huge loss and the disorientation they're suffering from, because there is a huge vacuum of power now within al-Qaeda," he said.
"It's an empty threat. But we are fully alerted. We have a very, very well and detailed plan to secure Baghdad and to secure Diyala and to secure other parts of Iraq, and we're going to stand and protect our people," he said.
"Those operations or those attacks that he has planned, and they are already in the pipeline and they're in the final stages of carrying them out, will be carried out, and it will happen," Mr Rubaie said.
The commander of US-led forces in Iraq, General George Casey, said the al-Qaeda reaction was fully anticipated.
"I expect them to say what they said. I expect them to try and do what they said," General Casey told Fox News.
"I think what you're going to see is an enhanced security operation here announced by the Prime Minister (Iraqi Prime Minister Nuri al-Maliki) in Baghdad over the course of the coming week, and a tightening of security in the Baghdad area," the general said.
He said that Wednesday's military strike near the city of Baquba, northeast of Baghdad, did untold damage to the international network.
Intelligence treasure trove
Meanwhile the strike on Zarqawi has yielded a treasure trove of vital intelligence information, Mr Rubaie said.
"We found a lot of material in that place. We found the diaries. We found telephone numbers. We found computers, and ... there was a database in that computer," he said.
"There was a lot of information ... Zarqawi used to carry with him," he said.
"It was very, very useful, not only to capture Zarqawi and get him out of the way of the Iraqi people, because he's the number one enemy of the Iraqi people. It was the value of the information we got with him," said Mr Rubaie.
He said that the information was used to carry out "a lot of raids immediately after we got Zarqawi."
The security adviser said the information recovered from the military strike also led officials to other operatives in the network.
"We got quite a few of not only Abu Musab al-Zarqawi but others now in the organisation," he said.
"Without detailing anything, to not to jeopardise our security plan and our security operation, I can tell you that we have managed to inflict heavy casualties on this organisation when we got to Abu Musab al-Zarqawi," Mr Rubaie said.