He was sentenced to 25 lashes earlier this week over his depiction of conservative lawmaker Ahmad Lotfi Ashtiani as a soccer player.
A British Foreign Office statement said, "Charges should never have been brought at all for this innocuous act, but it is sadly not surprising given the government has consistently shown such flagrant disregard for its citizens' rights and freedoms."
Ashtiani is among politicians being criticized for interfering in sports.
In an earlier joint statement, a dozen Iran-based websites condemned Shokraye's sentence and warned that it sets a dangerous precedent.
The statement noted that drawing cartoons of politicians, including of Iranian presidents and other top officials, is common in Iran.