The Foreign Secretary Jack Straw has said the bomb attacks in Basra will not delay the transfer of sovereignty back to the Iraqi people.
Children travelling to school in buses were among those killed
A series of explosions in the southern Iraqi town on Wednesday killed almost 70 and left five UK soldiers injured.
Mr Straw, who said those responsible sought division and instability, said the coalition wanted new UN support.
Brigadier-General Mark Kimmitt warned more attacks were likely in the run-up to the handover of power.
The bombings outside police stations, which also killed children travelling in school buses, raised concerns violence was spreading to south Iraq.
The five UK soldiers from the Royal Welch Fusiliers- one of whom was seriously wounded - are thought to have been hit at a police academy in Zubair, 25 km (16 miles) south of Basra.
BBC correspondent Dominic Hughes said on Thursday British forces would be trying to rebuild the "battered" trust of people in Basra.
He said: "The British forces will have prided themselves before yesterday on having built up a good relationship with the people of Basra.
British forces must try to rebuild the trust of people in Basra
"We can see it was a calm place considering the rest of southern and central Iraq was seeing some quite severe violence."
He said it seemed likely the attackers had come from outside the city, and perhaps even Iraq, but it was still unclear exactly who was responsible.
Mr Straw, speaking at the Mansion House in London on Wednesday night, said: "Those who perpetrated such atrocities seek division and instability to advance their own agendas.
"Their greatest fear is a democratic and pluralist Iraq. Our commitment to defeat them is firm.
"We will stick to the date of 30 June for the transfer of power. We will work for a new UN Security Council resolution."
Brigadier-General Kimmitt, the deputy director of coalition operations, warned disaffected groups might strike again.
He said: "As we get closer and closer to handing over governance to the people of Iraq... there will be numbers of groups inside the country that don't want to see Iraq transformed into a flourishing democracy.
"They will try everything they can to avoid this happening.
"Our assessment is this is yet another attempt to derail the process of turning Iraq into the model of democracy in the Middle East."
Prime Minister Tony Blair said the attackers were terrorists who aimed to prevent a "stable.. democratic Iraq".
He said it was not necessary to send extra troops to UK-controlled southern Iraq but that the situation was always under review.
Previously much of the worst violence in Iraq has been confined to Sunni areas of Iraq such as Baghdad and Falluja, under American control.
Britain has suffered far fewer casualties, although recently soldiers have been injured in Amara.