The call came as several thousand Islamists and members of leftist parties rallied in the capital Amman to keep up pressure on a government they blame for worsening the plight of the poor.
The price hikes include a 54 percent increase in the cost of gas cylinders used for cooking and heating. Much of the unrest since mid-November has hit impoverished towns across the country of 7 million.
The protesters called for the removal of Prime Minister Abdullah Ensour and urged citizens to rise up against the price rises, which the government says are necessary to bring stretched state finances under control.
Officials from the Muslim Brotherhood, the country's largest political party, say the authorities should form a more credible, broad-based government to restore stability.
"Wisdom is needed by the authorities to defuse the crisis the country is facing and to respond to people's demands to abolish price increases and form a government of national salvation," said Sheikh Hamza Mansour, head of the Islamic Action Front, the political arm of the Brotherhood.
He warned: "Unless the state backs down, the nation is open to all possibilities."
Opposition politicians blamed Jordan's financial problems on the ruling elite's failure to punish corruption among top officials.
"The Jordanians are thirsty for reforms," Ahmad Obeidat, a former prime minister and spy chief, told the crowds in Amman.
Jordan has witnessed several bouts of civil unrest in poorer provincial regions in recent decades, usually caused by rising prices of essential goods.
The latest protests have galvanised more of the population - the Brotherhood is a mainly urban movement - but not yet acquired the kind of critical mass that led to the toppling of leaders in Tunisia, Egypt and Libya last year.Prime minister under pressure
Ensour's government faces a weak economy and a steep drop in foreign aid that leave it with less money to distribute among the population in the form of jobs and subsidies.
Much of the unrest has been in tribal areas that form the backbone of support for the monarchy and rely heavily on state employment and welfare.
Political analysts say the price rises could boost the popularity of the Islamist opposition, emboldened by last year's Arab uprisings.
Scattered calls for the downfall of King Abdullah in the early days of the unrest have fizzled out for now. The 50-year-old monarch is still seen by most of Jordan's competing factions as a safeguard of national unity.
Protesters now mostly vent their fury on Ensour and his cabinet.
"Go Ensour, Go Ensour," the crowd shouted on Friday.
"Just continue to raise prices and protect thieves and let people burn," chanted some.
Hundreds of bearded youths cried: "People have had enough of staying silent". Activists waved banners bearing slogans against "theft of public money" and "rampant corruption".
The Brotherhood, the country's largest political party, and its leftist allies say political freedoms in Jordan have eroded in recent years. They say reforms since the wave of Arab revolts fall short of demands for wider political representation.
The authorities accuse them of fomenting unrest and of refusing to join a reform dialogue launched by the king in 2011.
AMMAN, Jordan (Reuters) -- Jordan's Islamist opposition urged King Abdallah to form a government of national salvation on Friday to calm street protests sparked by steep increases in fuel prices.