ATHENS—Greek Prime Minister Alexis Tsipras lashed out at European nations Friday for their handling of the migrant crisis, accusing them of shedding ”crocodile tears for dead children.”

His unusually harsh comments come as the death toll in the Aegean Sea from refugees and other migrants continues to rise. On Friday, 22 people drowned, including children, in two separate incidents involving boats sinking off the islands of Rhodes and Kalymnos, close to the border with Turkey.

“I...