Its shares came off record high levels in after-hours trading when it revealed it sold 50.7 million iPhones over the three months to 1 April - down from 51.19 million in the same period a year earlier.
It is a sign, analysts said, that customers may be holding off purchasing an iPhone until the 10th-anniversary edition launch of the company's most important product - expected this September.
The iPhone 7 and iPhone 7 Plus were selling well, the company insisted though the numbers were 1.5 million shy of estimates.
It reported revenue up 4.6% to $52.9bn in the quarter, also short of expectations, though profits rose 5% to just over $11bn.
The iPhone number was the biggest surprise in the results as sales usually soar once prices tend to ease after the Christmas season.
Demand then traditionally tails off ahead of the launch of the next range - which is tipped to include features such as wireless charging, 3-D facial recognition and a curved display.
The iPhone 7 series got mixed reviews - although longer battery life was welcomed, as were camera improvements in the iPhone7 Plus.
Chief (Taiwan OTC: 3345.TWO - news) executive, Tim Cook, said: "We are proud to report a strong March quarter, with revenue growth accelerating from the December quarter and continued robust demand for iPhone 7 Plus.
"We've seen great customer response to both models of the new iPhone 7 and we're thrilled with the strong momentum of our Services business, with our highest revenue ever for a 13-week quarter."
Its share price has risen more than 25% this year as investors speculate that US President Donald Trump will help firms repatriate massive cash piles from abroad, at a reduced tax rate, to aid the country's economy.
Apple has more than $230bn offshore alone.
Despite hopes of a hint as to what Apple might do, it gave no suggestion of possible plans.
There has been speculation it could go on a corporate buying spree to raise its entertainment interests.