"Turkey may buy Patriot systems in the future. But it will be impossible if abandoning S-400 will be one of the conditions for the purchase," Cavusoglu told the NTV broadcaster.
Earlier, a Bloomberg report cited two sources familiar with the discussions as saying that Turkey had allegedly suggested US technical experts delve into the S-400 systems in order to "control damage" in relations with Washington.
Commenting on this report, Turkish Defence Minister Hulusi Akar categorically rejected these claims, saying that Ankara never suggested US technicians should study the Russian-made S-400 missile system.
Ankara signed a loan agreement with Moscow envisaging the deliveries of the Russian-made S-400 air defence systems to Turkey last December.
The US government has repeatedly expressed concern over Turkey's decision to go on with the purchase of Russia-made missile defence systems, threatening to block the delivery of F-35 fifth-generation fighter jets to Ankara.
Recently, a US delegation made an official offer to Turkey to purchase US-made Patriot air defence systems, according to the Anadolu news agency. Four AN/MPQ-65 radars, 10 antenna-mast units, 20 M903 launching stations, and test equipment were listed in the offer.