The premier dismissed the ministers for justice, interior, and energy and environment after they refused to support his finance minister.
The Balkan state's politics are notoriously shaky, with two general elections in the past 18 months, but Premier Andrej Plenkovic dismissed the ministers for justice, interior, and energy and environment after they refused to support his finance minister.
The split stems from huge troubles engulfing retail giant Agrokor, the country's largest employer, which is saddled with six billion dollars of debt.
The credibility of Plenkovic's Finance Minister Zdravko Maric, whom the opposition want fired, has come under scrutiny as he was formerly a top manager at Agrokor.
The failure of the three ministers, all from a junior coalition partner, to support Maric prompted Plenkovic to sack them, endangering his fledgling government.
"New elections are not realistic, but if they take place I'm ready," the prime minister told reporters.
Only one minister remains in the government from the junior ruling party "Most" (meaning "Bridge" in Croatian).
Most's leader and parliamentary speaker Bozo Petrov accused the prime minister of "toppling the government".
Plenkovic, who heads the conservative HDZ party, came to power after an early general election in September.
The previous barely-functioning coalition government, also involving HDZ and Most, collapsed last June over a conflict of interest scandal after just five months in power.
The HDZ has 58 deputies in the 151-seat assembly but Plenkovic told reporters he enjoyed the support of a parliamentary majority, hinting that he could reshuffle the ruling coalition without Most.
But political analyst Ivan Rimac said the move was a "very serious blow" as Plenkovic had given up "three very good ministers".