The Primera Division side's president Jose Maria del Nido was left fuming at the French outfit over their behaviour during the switch, but PSG say they did not break any rules
The former Lorient star signed a five-year deal with Sevilla on Thursday after protracted talks between both sides, and Del Nido was not amused with the Ligue 1 champions' attitude during negotiations.
"We were mistreated by PSG and that's an understatement," Del Nido said at a press conference.
"We had agreed that we would pay €3 million right now, then €2.5m next year and €2m in 2015. But then in the end they all of a sudden demanded we paid the entire sum right away.
"And this is just one example of many more events. Each problem was followed by the next problem. This must be the worst transfer talks I have ever been involved in. Fortunately, the player really pushed hard."
PSG, meanwhile, have stressed they did not do anything out of the ordinary during talks over Gameiro's transfer.
"Paris Saint-Germain are committed to respecting the rules of courtesy and professionalism during transfer talks. When it comes to the transfer of a player, it's legitimate to ask for a bank guarantee from the buying club," a statement on the club's official website reads.
"If difficulties arise, we will look for an alternative payment method. This is what happened in the case of Kevin Gameiro's transfer. PSG have done everything to facilitate this transfer and allow Sevilla to complete the deal quickly."