"I shall not allow any faltering of the reform process which I began when I took the reins of power," King Hamad said in a statement on the official BNA news agency.
"The door is open on any subject that is in the interest of all the citizens," he said.
Opposition groups demanded on Saturday "the establishment of the right environment to start political dialogue" without clarifying if their demand for the government to resign has been dropped.
Meanwhile, the body of protester Issa Abdali Radhi, who had been missing since clashes on Tuesday in the village of Sitra, south of Manama, was found in Manama's Salmaniya hospital morgue, his brother Jalil told AFP.
"My other brother went and confirmed that it is him," he said on Saturday, adding that the medical report showed that Radhi, 47, was "killed by gunfire."
The funeral of Ahmed Abdullah, who was shot at a protest west of Manama on Wednesday, was held on Friday, opposition MP Mattar Mattar said, adding that security forces had prevented Abdullah from being taken to Salmaniya hospital for treatment.
Bahrain faces mounting international pressure to exercise restraint and ensure the safety of jailed opposition leaders.
On Friday, the United States said it was "deeply troubled" by the arrest of several opposition figures and activists.
"We call on the government of Bahrain to abide by its commitment to transparent judicial proceedings conducted in full accordance with Bahraini law and Bahrain's international legal obligations," said State Department spokesman Mark Toner.
Washington also called on Bahraini "security forces to cease violence, especially on medical personnel and facilities," and observe "maximum restraint," he said, also calling on protesters to "engage peacefully."
The government has launched a bloody crackdown to stop Shiite-led protests, declaring martial law and rounding up dissidents at gunpoint in midnight raids.
And on Saturday, BNA reported that Bahrain Defence Forces have banned maritime activity in various areas of the Gulf archipelago's waters at night until further notice.
But it reduced curfew hours in parts of Manama's business district and the government called on public sector employees and teachers to return to work from Sunday while students will remain home until further notice.
The return to work comes despite the continuation of a general strike called for by Bahrain's main trade union in protest at the violent repression of protests.
Traffic in central Manama got close to normal levels during the day, but only police and army patrols were moving at night as the curfew started.
Opposition groups urged authorities on Saturday to release political prisoners and "reveal the whereabouts of the missing and detainees", holding the "government responsible for their safety."
The alliance of six groups, including the main party Al-Wefaq, also called for "an immediate stop to sieges and attacks targeting hospitals" and the withdrawal of "armed militias" from the streets.
Foreign Minister Sheikh Khaled bin Ahmad Al-Khalifa said Friday that dialogue "under current tensed conditions cannot take place" and that "priority is for security and stability."
Crown Prince, Sheikh Salman bin Hamad, under the auspices of his father King Hamad, offered the opposition an open dialogue after a deadly crackdown on protests last month instigated a sit-in at Manama's Pearl Square.
Five people were killed on Wednesday, including two police, as security forces dispersed the crowd at Pearl Square, after a Saudi-led military contingent entered the Gulf state to back up the regime.
Thousands of the Shiite-majority community protested in villages on Friday as riot police and army, backed by the joint Gulf force, kept tight control of the country ruled by the Al-Khalifa dynasty.
The violence in the strategic Gulf state sparked furious condemnation from Iran, Iraq, the Hezbollah militia in Lebanon, and protesters in nearby Saudi Arabia.
Protesters in Iran's north eastern city of Mashhad stoned the Saudi consulate on Friday.