Koca entered the field and hit the referee when the final whistle blew in the 1-1 draw at Eryaman Stadium, footage from state broadcaster TRT showed.
Ankaragucu fans invaded the pitch after the game and Meler was also kicked when he fell, though it was unclear who his assailants were. Meler eventually made it to the dressing room with the help of the police.
"The Turkish Football Federation has decided to suspend all games in all leagues indefinitely," the federation posted on X.
"The related club, the club chairman, club officials and all those guilty of attacking referee Umut Meler will be punished in the strongest terms possible."
A detention order has been issued for Koca, Interior Minister Ali Yerlikaya said in a post on X, adding that two people have already been detained as part of a judicial investigation into the incident.
"Turkish football has been punched shamefully tonight. Everyone involved in this incident will pay the price," TFF Chairman Mehmet Buyukeksi said, according to TRT.
A FIFA referee since 2017, 37-year-old Meler took charge of Lazio's Champions League group game with Celtic on November 28th.
Turkish President Recep Tayyip Erdogan tweeted: "Sport means peace and brotherhood. Sport is incompatible with violence. We will never allow violence to take place in Turkish sports."
Referees in Turkey are often criticised by club managers and presidents for their decisions but are rarely the target of violent attacks.
Ankaragucu are 11th in the standings on 18 points, three places below Rizespor on 22 points after 15 matches.
