The quick reaction of security forces was praised
"The explosion occurred in a vehicle in the staff car park adjacent to the High Commission," said Rachel Jameson, a spokeswoman at the commission.
"It appears as if it was an explosive device."
Superintendent Nasir Khan Durrani, of the Islamabad police, described the device as a "low intensity bomb"
It had been put in the boot of a Toyota mini van used by the commission for transporting Pakistani employees there, Mr Durrani said, according to the AFP news agency.
Strengthened security
It caused little damage.
"When we checked this Toyota Coaster's boot, there was a hole which was almost three inches (7.5 cm) in diameter and from there we collected some explosive material," added Mr Durrani.
No-one has admitted they carried out the attack.
British Foreign Secretary Jack Straw said he was awaiting the result of an investigation into the blast.
"I am concerned by news of the explosion at the High Commission in Islamabad and relieved that there are no casualties," he said in a statement.
"I welcome the rapid reaction of the Pakistani authorities and look forward to the results of their investigation.
"I have spoken to the High Commissioner, who has confirmed that all necessary measures are being taken to ensure the safety and security of staff."
More than 50 police, many carrying riot shields, stood guard around and outside the car park after the explosion although embassy vehicles were still free to come and go.
On alert
Police said the explosion was around 11.45am (0645 GMT).
Since the 11 September attacks in the United States, security has been strengthened around diplomatic missions in Pakistan.
President Pervez Musharraf has pledged to reduce the level of violence within Pakistan.
"Violence and terrorism has been going on for years and we are weary and sick of this Kalashnikov culture," he told the nation earlier this month.