Spain coach Luis Enrique said on Sunday the fans who have abused Alvaro Morata and his family committed a "serious crime" and should be investigated by the police.

Morata told Spanish radio station Cadena COPE on Thursday night his wife and children had been subjected to abuse by fans in Seville, with the striker under pressure after missing chances during Spain's three group games at Euro 2020.

"People have said 'I hope your children die'. I've had to put my phone away," Morata said.

"My children go to Seville with their dad's name on their shirts. I understand criticism for not doing my job well. But there's a limit."

Luis Enrique was asked about the issue in a press conference ahead of Spain's last-16 game against Croatia on Monday.

"It's bad enough that it should be put in the hands of the police," Luis Enrique said. "It is a serious crime. Insulting his family is a serious issue that has to be put into the hands of the authorities and dealt with in the strongest possible way. It is his wife and children."

Morata was whistled when substituted in the first game against Sweden, which ended goalless, and he missed a penalty in Spain's 5-0 win over Slovakia, as the team went through second in Group E.

"We're all used to criticism but we do not accept threats to a player, his family, and his kids," said Spain midfielder Koke.

"After the last game, I gave Alvaro a big hug. You help him by being as normal as possible and trying to make sure his mind is on what it should be on.

"I love him. Apart from being a player and a team-mate, he is my friend."