The British Embassy has denied the charge and condemned the blasts.
Thousands of people took part on Monday in the funeral in Ahvaz, Khuzestan province, of the six people who were killed when bombs exploded on Saturday in a shopping centre in the southwestern town.
Some mourners accused Britain of instigating the blasts, which wounded at least 102 people.
"We are extremely suspicious that there was a British forces' role in the terrorist attacks," state TV quoted President Mahmoud Ahmadinejad as telling the cabinet on Sunday.
"Iranian agents have found the footprint of Britain in previous cases."
On Sunday, Iranian Interior Minister Mostafa Pourmohammadi said he believed the Ahvaz explosions were a continuation of previous explosions which he claimed were guided from abroad.
In June, four bombs in Ahvaz killed at least eight people.
Dozens of people have been
injured in the latest attack
Iran blamed them on Iranian Arab extremists with ties to foreign governments, such as Britain.
Ahvaz is close to the border with southern Iraq, where 8500 British soldiers are based as part of the US-led military coalition.
The city suffered two days of riots in April after reports circulated that the government planned to reduce the town's Arab majority in favour of Persians.
The government denied the reports.
"Any linkage between the British government and these terrorist outrages is completely without foundation," the British Embassy in Tehran said in a statement on Sunday.
In recent weeks, Tehran has accused Britain of provoking unrest in oil-rich Khuzestan.
And Britain has accused Iran of supplying fighters in southern Iraq with sophisticated bomb technology. Both countries have denied the respective claims.