“Many international organizations consider what happened to be extrajudicial killing,” a statement carried by Hezbollah’s media office said.
The high court had upheld death sentences against three anti-regime activists over their alleged role in a 2014 bomb attack, amid widespread public anger against the death verdicts.
“This execution will topple any opportunity to reach a political solution to the crisis in Bahrain,” Hezbollah said, the Daily Star reported.
Bahrain, which has been ruled by the Al-Khalifa dynasty for more than two centuries, has given a heavy-handed security response to peaceful popular protests, which first began in early 2011.
Sheikh Abdel-Amir Qabalan, vice-president of the Higher Shiite Council in Lebanon also denounced the execution of the three Bahrainis, saying that they were among the political detainees.
“The execution exacerbated the political crisis in Bahrain,” Qabalan said.
He also urged the Bahraini government to initiate a reconciliation process with the people and to resort to dialogue with religious and political figures of the opposition.
The men who were executed have been named by activists as Sami Mushaima, 42, Ali al-Singace, 21, and Abbas al-Samea, 27.
Both Hezbollah and Sheikh Qabalan offered their condolences to the families of the three men and the Bahraini people.