Recep Tayyip Erdogan has rejected a call from Donald Trump to declare a ceasefire and halt Turkey's military offensive in Syria.
Turkey's leader said he is not concerned about the presence of Syrian government troops moving into the city of Manbij.
US President Trump earlier announced sanctions on Turkey in response to its military offensive against Kurdish fighters in Syria.
He called for an immediate ceasefire.
Mr Erdogan has since responded by saying: "They say 'declare a ceasefire'. We could never declare a ceasefire."
Turkey launched its military offensive a week ago to clear a border region from Syrian Kurdish forces linked to outlawed militants.
Mr Erdogan said that "we cannot declare a ceasefire until we clear this region".
His comments came during a flight back from Azerbaijan, first reported by the Turkish newspaper Hurriyet
Mr Trump has announced sanctions on Turkey in response to its military offensive against Kurdish fighters in Syria.
The US President said the sanctions were being imposed on three senior Turkish officials and the country’s defence and energy ministries.
He said he was also halting negotiations on a $100 billion trade deal with Turkey and raising steel tariffs.
“I am fully prepared to swiftly destroy Turkey’s economy if Turkish leaders continue down this dangerous and destructive path,” he said.
A week earlier Mr Trump vowed to “obliterate” Turkey’s economy if the military did anything “off limits”.
He is also withdrawing US troops from northern Syria, following a call with Turkey’s leader.
