The intervention by Oana Lungescu, a Nato spokesperson, comes after Turkey's foreign minister warned the country would consider leaving Nato if the organisation did not come to its defence, following the perceived lack of support following the failed coup.
Relations between the EU and Ankara have worsened since the recent attempted military coup.
In an interview with the state-run Anadolu agency, Mevlut Cavusoglu claimed the European Union was fuelled by anti-Turkish sentiment and hostility to President Recep Tayyip Erdoğan.
He accused the EU of making grave mistakes in its response to Turkey's failed coup and said the Union could only blame itself if the west "loses" Turkey.
Turkey is Nato's second largest military power after the US. It is a crucial ally as the west faces unprecedented conflict and upheaval across the Middle East.
Russian President Vladimir Putin and Erdoğan took a big step towards normalising ties on Tuesday, with their leaders announcing an acceleration in trade and energy links.
However, Nato responded by saying that Turkey's membership was not in question and that Ankara could count on its solidarity and support after the coup bid, which has triggered deep purges in the alliance's second-largest armed forces.
On Thursday, Oana Lungescu said, "In view of speculative press reports regarding Nato's stance regarding the failed coup in Turkey and Turkey's Nato membership, let me stress Nato's very clear position.
"Turkey is a valued ally, making substantial contributions to Nato's joint efforts. Turkey takes full part in the Alliance's consensus-based decisions as we confront the biggest security challenges in a generation."
She added, "Turkey's Nato membership is not in question. Our alliance is committed to collective defence and founded on the principles of democracy, individual liberty, human rights and the rule of law.
"Nato counts on the continued contributions of Turkey and Turkey can count on the solidarity and support of Nato.”