Nectar also pledged to invest 6.0 million euro in Heba, the agency said in a statement late on Thursday but did not give a timeframe for the investment programme.
The agency opened sales talks with Nectar in September, after ranking it first ahead of the other bidder, Serbian firm Roaming Electronics.
Serbia opened the tender for Heba in April and later extended once the initial bid-filing deadline.
Heba ranked Serbia's fifth biggest water bottler in 2007 with a market share of seven percent, according to data from Heba's prospectus published on the Privatisation Agency's website. Local company Knjaz Milos had the largest market share of 31% in 2007, followed by BB Minaqua, Voda Vrnjci and Rosa.
Nectar is active in the production, processing and packaging of fruits and vegetables. It produces fruit juices, syrups, marmalades, fruit brandies and apple vinegar.
($=0.7985 euro)