A spokesman for the Kurdish militia said his fighters downed the chopper in Raju, northwest Afrin.
"A little earlier, one of our helicopters was shot down", Erdogan said in televised remarks without saying who was responsible but vowing they would pay a "heavier price".
According to the Turkish General Staff, the operation aims to establish security and stability along Turkey's borders and the region as well as to protect Syrians from terrorist oppression and cruelty.
"We don't have exact evidence or document to determine that it went down with any outside interference", said Binali Yildirim.
Turkish soldiers and Free Syrian Army (FSA) fighters have cleared Sharran town's Serincek village of PKK-linked People's Protection Units (PYD) terrorists in Syria's northwestern Afrin region, according to Anadolu Agency correspondents on the ground Sunday.
But tensions have mounted in recent months, with Damascus threatening to march into parts of eastern and northern Syria captured by the SDF with support from the US -led coalition. But Afrin is separated from the bigger Kurdish-controlled region further east by a 100km-wide zone controlled by the Turkish military and its Syrian militia allies.
SYRIAN regime air strikes killed six civilians, including two children, overnight in Eastern Ghouta, after a day of respite from deadly bombardment of the rebel enclave, a monitor said today.
According to the statement, the United Nations office staff has received reports and video footage suggesting that "toxic agents" may have been released following airstrikes Sunday on a residential area of Saraqeb.
Western powers have expressed alarm over the government's campaign against rebel-held Eastern Ghouta, where 400,000 people have been besieged since 2013.
"Even by Syria's atrocious standards, these are exceptionally deplorable developments - and a cruel irony given that both have been declared "de-escalation areas", said Mr Al Hussein.
"The conduct and management of this war has been utterly shameful from the outset, and the failure to end it marks an epic failure of global diplomacy".
A spokesperson for the United Nations chief said: "The Secretary-General stresses once again that all concerned in Syria and the region have a responsibility and must abide by worldwide law and relevant Security Council resolutions".