Slovenia promised to sell 50 percent of NLB this year and another 25 percent in 2018 in exchange for the European Commission's approval of state aid to the bank in 2013.
The government, in a statement, said state-owned Slovenian Sovereign Holding (SDH), which is coordinating the NLB sale, set a price range of 55 to 71 euros per share, which would value the bank at 1.1 billion euros to 1.4 billion euros ($1.2 bln-$1.6 bln).
"The government has not approved the minimum sale price," Cerar told reporters after a cabinet meeting, adding it would seek a solution with the European Commission.
The Commission said talks would continue.
"We are in constructive contact with the Slovenian authorities. We cannot speculate further at this stage," a spokesperson for the European Commission said.
Analysts said the government would get about 1 billion euros at most for the whole bank, significantly less than 1.55 billion euros it put into the bank in 2013 to prevent it from collapsing under a large amount of bad loans.
Last month the government also refused to give guarantees for what could amount to about 400 million euros in compensation to Croatian banks, who repaid depositors of NLB's predecessor Ljubljanska Banka and are now demanding the money from NLB.
Ljubljanska Banka closed its business in Croatia after Slovenia declared independence from the former Yugoslavia in 1991 and Slovenia wants the repayment agreement to be part of succession talks between the ex-Yugoslav states.
Slovenia has been reluctant to privatise its major companies and banks in recent decades so the government still controls about 50 percent of the economy and about 44 percent of the banking sector.
NLB is the biggest company on the government's privatisation list and no other major sales are expected before a general election which is due in the middle of 2018.
Slovenia sold 34 percent of NLB to Belgian banking group KBC in 2002 but later refused to allow KBC to acquire a majority stake in the bank. In 2012 KBC sold its stake back to the state.
