Kyrgios, 21, reacted after apparently being disturbed as he prepared to serve in Tuesday's 3-6 6-3 6-3 win.
The world number 17 later laughed off Australian broadcaster 7 News' report that four fans want an apology.
Sela confronted Kyrgios after the match at the Abierto Mexicano Telcel, with the umpire coming between the players.
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The incident is the latest in a string of controversies for Kyrgios who accused an umpire of being biased in his semi-final defeat by Jo-Wilfried Tsonga in Marseille last week.
He was banned for eight weeks and fined for his on-court behaviour at October's Shanghai Masters, although he accepted a 'care plan' agreement that would reduce the suspension to three weeks.
Kyrgios will play former world number one Novak Djokovic in the last eight from 04:00 GMT on Friday morning.
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Australian Nick Kyrgios has told a group of opposing fans to "man up" after swearing at them in his win over Israeli Dudi Sela in Acapulco.