Operations at JKIA are running normally despite confrontations between police and NASA supporters outside, KAA has said.
Kenya Airports Authority responded on Friday after a notice, now dismissed as fake, stated
international flights had been diverted to Eldoret, Mombasa and Kisumu airports.
The notice should be disregarded, the authority wrote on Twitter.
"Operations at JKIA are running normally. Kindly disregard the communication currently circulating on social media saying the contrary."
Earlier, Fly540 asked passengers to print their tickets or have soft copies before getting to the JKIA.
"Please arrive at least an hour before your flight due to long security lines at the entrance."
Anti-riot police fired in the air and hurled tear gas canisters to disperse NASA supporters who were marching to JKIA to welcome their leader Raila Odinga.
Despite the partial ban on protests in Nairobi, the demonstrators gathered near the airport to wait for the return of their leader from a US trip.
The demonstrators hurled rocks at the anti-riot
police who were trying to disperse them.
The crowd, which had blocked Mombasa Road, also engaged police in running battles at Cabanas area.
The supporters were chocked as the tear gas filled the air but some still waved placards and twigs and made fun of the officers.
Opposition leaders on Thursday said they will mobilise at least a million people to welcome the NASA chief back from the US.