"From a demand point of view, it's hard to gauge when you don't have product in stores," said Cook.
Apple is only selling the watch online and in select third-party boutiques due to the large number of models and straps for the watch, which could become a logistics nightmare if it offered every permutation of the many varieties at already jam-packed Apple stores.
The California tech giant said profit rose 33 percent from a year ago to $13.6 billion, lifted by sales of 61 million iPhones in the first three months of the year.
Revenue increased 27 percent from the same period a year ago to $58.01 billion, Apple said.
Cook said the iPhone "led the way" in its massive increase in China sales. Apple saw an increase in revenue in the country 71 percent to $16.8 billion, although that was helped by gift-buying for Chinese New Year.
Chief Executive Tim Cook said that China's expanding middle class is fuelling iPhone sales there, which is the bulk of the company's sales. The iPhone 6 was launched last autumn in China with a number of carriers.
Apple sold 61.2 million iPhones in the quarter, up 40 percent from the year-ago quarter, but down from the record-breaking holiday quarter. It sold 12.6 million iPads, down 23 percent from a year ago.
Apple's big screen iPhone 6 (Review | Pictures) and iPhone 6 Plus (Review | Pictures) have been popular with customers worldwide, helping the company overtake rival Samsung in global smartphone sales last quarter.
Edited by NDTV staff from original story by Reuters