Pope Francis has urged Christians to pray for God to reach the hearts of terrorists and stop them from sowing "death and destruction".
At the end of his general audience in Rome on Wednesday, the Pope highlighted the coordinated attacks in "beloved Syria" on May 23, referring to the victims as "defenceless civilians".
More than 160 people were killed in a series of explosions in Jableh and Tartus – government stronghold cities on the west coast of Syria – on Monday.
It was the first time civilians have been targeted in this way in the two cities since the beginning of Syria's civil war, which entered its sixth year in March.
Islamic State has claimed responsibility for the attacks.
In St Peter's Square, the Pope called on those present "to pray to the merciful Father, to pray to the Madonna, that [God] might give eternal rest to the victims, and consolation to their families, and might convert the hearts of those who sow death and destruction," according to Vatican Radio.
His words follow the assertion of Vatican official Cardinal Kurt Koch, who last week said Christians have a "mission to convert" all people except Jews, including Islamic extremists.
The Pope also warned that "prayer is not a magic wand", but is instead a tool of faith.
"God promptly answers promptly his children, although this does not mean he does it in the time and manner that we would like," he said.
"It helps to preserve our faith in God, and to trust in Him even when we do not comprehend His will. In this, Jesus himself – who prayed so much! – is the example."