Flags were flown at half-mast across Turkey and at its missions overseas on Friday as the country marks a day of national mourning for Hamas’ political leader, Ismail Haniyeh.
He was assassinated on Tuesday in the Iranian capital, which Tehran and other countries in the region have blamed on Israel.
Israel has not confirmed or denied its involvement in his death.
It had pledged to kill him and other Hamas leaders over the group’s 7 October attack on Israel last year, in which some 1,200 Israelis died and more than 250 were taken hostage.
On Friday, Israel summoned the deputy Turkish ambassador for a reprimand after Turkey’s embassy in Tel Aviv lowered its flag.
Israel, like many Western nations, sees Hamas as a terrorist organisation, while Turkey’s President Recep Tayyip Erdogan frequently describes the Palestinian group as a “liberation movement”.
He issued a presidential decree for flags to be flown at half-mast on Friday and denounced the killing of Haniyeh as a “despicable” act.
Turkey meanwhile blocked access to Instagram on Friday.
While it did not provide a reason, various media said the move came after the social media platform took down posts expressing condolences at Haniyeh’s passing.
Relations between Turkey and Israel have dramatically worsened since the start of the war in Gaza, in which more than 39,000 Palestinians have been killed.