The industry sub-index for September rose 1.8 points on the month, as managers were more optimistic about the business in the next three to six months, NSI said.
Managers said they expect fewer foreign orders but this did not affect the outlook for production activity.
Low domestic demand, insecure global economic environment and shortage of labour force partly curbed optimism and led to expectations for higher prices.
In September, the construction sub-index lost 4.9 points, as managers were pessimistic about their three-month operations with the summer season coming to an end.
The survey indicated a decrease in the number of clients falling behind on their payments.
Overall, 35.9% of managers said they plan to hike prices, while the majority will keep them unchanged through December.
The sub-index in the retail sector dropped by 3.1 points from the previous month, as managers were moderate in their expectations regarding the current and short-term state of the sector and the numbers of orders.
Fewer managers in the sector see a surge in retail prices in the next three months.
The index gauging the business climate in the services added 3.0 points in September. Managers said they expect conditions in the sector to improve or remain unchanged by December and most of them expect no inflation.