His form led to reports United were plotting a swoop for his services with the offer of a £150,000-per-week contract.
Asked how he dealt with the speculation, Niguez told Marca: "Well honestly very well.
"I am very flattered that a club like Manchester United or other teams that ask about me take me into consideration, for me it is very positive.
"And that strong people in those clubs speak well of you means that I am doing things well at Atletico Madrid."
Niguez played 47 times for Atleti last season, scoring seven times across the campaign in all competitions.