Following Southampton's 2-1 defeat, the club said they were taking "an extremely firm stance" over the incident, which took place during the game.
In a statement issued by the Saints, they said: "Southampton Football Club can confirm that two fans were detained and had their details taken by police during our match against Cardiff City on Saturday.
"The club will continue to work with Hampshire Police to identify any individuals deemed to have made indecent gestures towards Cardiff supporters.
"Such behaviour has no place in our game and will not be tolerated at St Mary's. The club will be taking an extremely firm stance against anyone involved and intends to ban those supporters identified."
Saturday's Premier League fixture, which saw a minute's silence observed before kick-off, marked the first time Cardiff have been in action since the 28-year-old's body was recovered from plane wreckage found in the English Channel.
The Argentinian, who was flying from Nantes to Cardiff, had become the Bluebirds' record signing with a £15m move to the UK.
The flight carrying Sala crashed into the English Channel near Alderney on 21 January. David Ibbotson, who was flying the aircraft, remains missing.
Saturday's game comes after Sala's former club Nantes said they would retire their No 9 shirt in honour of the footballer.