Koeman said on Saturday that he was "excited about the team" and urged them to avoid "living in the past" ahead of the first Liga match.
The Spanish Football Federation on Friday banned him for two games after the Dutchman was sent off during his team's 2-1 defeat at Granada.
Lionel Messi produced a hat-trick of assists as Barcelona pulled off a gutsy 3-2 win at Real Betis after trailing twice in an enthralling match in La Liga on Sunday, finally giving the Catalans something to celebrate after a week of upheaval.
Setien is to leave the club by mutual consent, the club said on Sunday after he enjoyed a memorable end to his two-year tenure by winning 2-0 at Real Madrid.
Liverpool have had one of their best seasons despite being on the prink of ending the season with no titles.
Liverpool players are searching for a miracle to reach the final after losing the first leg in Spain 3-0.
He has made just six appearances for Arsenal since making a temporary switch from Barcelona in January.
Messi has been central to Barcelona's success, scoring 42 goals across all competitions and proving the side's talisman time and again.
Barcelona defender Samuel Umtiti could resume training this month, coach Ernesto Valverde said on Saturday.
The Catalans were already short-staffed in central defence due to the prolonged absence of France international Samuel Umtiti.