The eight regional forces merged into Police Scotland on 1 April 2013 and official statistics show there were 172 officers fewer three months later.
The figure of 17,324 officers was also down 49 (0.3%) from April 2012.
But the Scottish government said it had maintained its pledge to put at least 1,000 more officers onto the streets than when it came into office in 2007.
The quarterly strength statistics are the first to be published since Police Scotland came into being – and do not offer a regional breakdown.
Work is continuing to harmonise data held by the previous forces to enable Police Scotland to be able to publish regional figures in the future.
Justice Secretary Kenny MacAskill said police numbers always fluctuate – but the current number is 6.7% higher than March 2007.
He said: “This government has kept its promise to protect police posts – in direct contrast to England and Wales, where police numbers have fallen to their lowest level in 11 years.”