A Downing Street spokesperson confirmed the meeting took place but no further details of the discussions were made available.
The three leaders met at Cameron's 10 Downing Street office on the sidelines of an international conference on Afghanistan here to discuss regional security issues.
The leaders discussed the regional situation, with particular reference to Afghanistan, Dawn News reported.
Afghan Chief Executive Abdullah Abdullah was also present at the meeting.
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At the conference inaugurated by UK foreign secretary Philip Hammond, Kerry renewed US commitments to Afghanistan.
"We will continue clearly to invest in Afghanistan's growth," Kerry said, adding that he had faith in President Ghani to create a "strong and prosperous" Afghanistan.
Ghani had sought guarantees from delegates that they would continue to invest after most foreign combat forces leave later this month.
"We will be with you every step of the way," Cameron told him.
Addressing the conference later, Ghani also pledged to continue reforms, saying that "history will not be repeated, we've overcome our past".