Apple's share growth in the smartphone market nearly paused in the second quarter of 2012 as consumers postponed their upgrade in anticipation of the upcoming launch of the company's new iPhone, a research firm said Tuesday.

In the quarter, Apple's iOS accounted for 18.8 percent of global smartphone operating system market, a slight growth compared with 18.2 percent a year ago, but was down 3.7 percentage points from the previous quarter, according to latest numbers released by the research firm Gartner.

Though still the number two in the smartphone market, Apple is seeing the gap between its system and market leader Android widened in the quarter.

Android captured 64.1 percent of smartphone operating system market share in the period, extending its lead with an increase of 20.7 percentage points year on year.

Apple sold 28.9 million iPhones in the second quarter, up 47.4 percent from a year ago but representing a decrease of 12.6 percent from the first three months of 2012, which showed consumers' demand for its iPhone weakened, said Gartner analysts.

Analysts also said the weakening demand was caused by users postponing their upgrade decisions in most markets ahead of the upcoming launch of iPhone 5, Apple's next generation of smartphones.

Apple may release iPhone 5 as early as in mid-September, according to U.S. media reports.

The arrival of the iPhone 5, a device expected to feature new design with a larger screen and likely other stylistic changes, will certainly make a strong case for users of Apple's old iPhone models to upgrade, Gartner analysts predicted.

Numbers from Gartner showed that worldwide sales of mobile phones, including smartphones, reached 419 million units in the quarter, a drop of 2.3 percent from a year earlier. Smartphone sales accounted for 36.7 percent of the total mobile phone sales in the period, with a growth of 42.7 percent year on year.