Samsung Electronics on Thursday offered a downbeat outlook for the second half of the year as smartphone market growth slows and ahead of the expected release of new iPhones from rival Apple. The firm also reported a 4 percent fall in second-quarter profit and ruled out a "special dividend" similar to a big year-end payout for 2014.

Samsung is facing the compatition at the low-to-mid end by Chinese rivals such as Huawei Technologies and in the premium segment by Apple. The company will be "adjusting" prices for the S6 and for the curved-screen S6 Edge to maintain sales growth, it said Thursday.

Samsung remained the top smartphone maker in April-June, but shipments fell in part due to an inability to build enough curved-screen Galaxy S6 edge handsets. The firm said its mobile division will launch new larger-screen phones in the third quarter but may not be able to improve earnings.

Second-quarter profit was 6.9 trillion won, matching the company's estimate issued earlier this month.

"While 2H 2015 is expected to present mounting challenges, the company will try to improve earnings," Samsung said on Thursday.

Samsung's mobile business booked a 38 percent decline in April-June operating profit at 2.76 trillion won.

The firm has brought forward the launch of its latest Galaxy Note phone to August from September, while reports also unveil plans for a larger version of the S6 edge.

On the bright side, Samsung's chips division reported profit of 3.40 trillion won, its highest since the third quarter of 2010, due to demand for memory chips and sales growth in mobile processors.