The Zimbabwean government has accused the UK of plotting an invasion and considering assassinations of the country's political leadership.
Robert Mugabe's government is subject to EU sanctions
Presidential spokesman George Charamba said Harare remained ready to defend itself against the "sinister threats".
He was responding to comments by former British general Lord Guthrie in a UK newspaper a week ago.
Lord Guthrie recalled advising the ex-Prime Minister Tony Blair against invading Zimbabwe.
Zimbabwe has often accused its former colonial ruler of attempts to interfere in its internal affairs, in part out of concern for white farmers - many of British origin - whose farms have been seized and redistributed.
But the UK accuses the government of President Robert Mugabe of gross human rights violations and of creating a "tragedy" in Zimbabwe.
In a frank interview with the UK's Independent on Sunday on 11 November, Lord Guthrie told the newspaper he had had a close relationship with Mr Blair.
"We used to talk about things," he said. "I could say anything to him because he knew I wasn't going to spill the beans."
Among the subjects they discussed, the newspaper reported, was an invasion of Zimbabwe, "which people were always trying to get me to look at. My advice was, 'Hold hard, you'll make it worse.'"
In his comments on Sunday, Mr Charamba told the official Sunday Mail newspaper that the Zimbabwean leadership had been aware of a threat of invasion.
"The government was aware of the plans and the president made reference to the sinister [British] motives on several occasions," he was quoted as saying.
"A defence plan had been operationalised and in fact, it is still in operation. We were also aware that short of a fully-fledged invasion, the British were and are still contemplating the elimination of our political leadership through a number of assassinations," said Mr Charamba.
Mr Charamba said the British government wanted to stage the invasion in pursuit of British national interests - and in particular the control of Zimbabwe's resources.
"Britain views Zimbabwe's white community as an extension of its nation and the invasion would not have been about politics but about British interests," said Mr Charamba.
Mr Mugabe, 83, faces a travel ban in Europe and his government is subject to EU sanctions. In addition to rights abuses, Western powers accuse him of bringing his country's economy to the brink of collapse.
Mr Mugabe says his country's economic hardships are down to Western sabotage.