Both the US State Department and British Foreign Office condemned the execution.
UK Foreign Minister Tobias Ellwood MP called on Iran to abolish the use of the death penalty.
"The UN noted that her conviction was allegedly based on confessions made while under threat. I urge Iran to put a moratorium on all executions," he said in a statement.
A campaign calling for a halt to the execution was launched on Facebook and Twitter last month and appeared to have brought a temporary stay in execution.
However, government news agency Tasnim said on Saturday that Jabbari had been executed after her relatives failed to gain consent from the victim's family for a reprieve.
It said her claims of self-defence had not been proved in court.