"There has been no such thing [an ultimatum] at the official level," Kiran said during his visit to the United States this week, as quoted by the Haberturk broadcaster.
The CNBC broadcaster reported on Tuesday, citing sources familiar with the matter, that Washington had given Ankara just over two weeks to give up its S-400 deal with Russia or else risk sanctions and losing the possibility of buying US F-35 fighter jets.
In December 2017, Moscow and Ankara signed a loan agreement for the delivery of S-400 air defence systems to Turkey. The United States has repeatedly warned Ankara against buying the Russian air defence systems, saying that they are incompatible with NATO systems and may expose weaknesses of the F-35 jets to Russia's advantage.
The United States earlier threatened Turkey with sanctions for its planned acquisition of S-400s and repeatedly said it may delay or cancel the sales of F-35 aircraft to Ankara.
The first batch of S-400s is expected to be delivered to Turkey in July.