The UK later said it had imposed an asset freeze and travel ban on Mohammad Jafar Montazeri, Iran's prosecutor general, "because he is and has been responsible for, engaging in, providing support for and promoting serious human rights violations in Iran."
"Sanctioning him underlines our disgust at Alireza Akbari's execution," Cleverly said. "The Prosecutor General is at the heart of Iran's use of the death penalty. We're holding the regime to account for its appalling human rights violations."
The execution looks set to further worsen Iran's long-strained relations with the West.
The relationship has deteriorated since talks to revive its 2015 nuclear deal hit deadlock and as Tehran unleashed a deadly crackdown on protesters last year.
In an audio recording purportedly from Akbari and broadcast by BBC Persian on Wednesday, he said he had confessed to crimes he had not committed after extensive torture.
Akbari, 61, was arrested in 2019 and convicted of spying for the UK, which he denied.
The Mizan report accused Akbari of receiving payments of $1.95 million, $323,989.00, and $50,000 for spying.