Euro 2024 security bulked after pitch invaders aim for Ronaldo selfies
The 39-year-old forward posed for a photo with a young boy during the 3-0 win over Turkey in Group F on Saturday in Dortmund, but grew exasperated as at least five more fans attempted to do the same.
"Safety and security in the stadium, on the pitch and at team facilities are the ultimate priority for UEFA," the European football governing body told AFP on Sunday.
"To this end, additional safety measures will be deployed in the stadiums to further meet the requirements of the tournament, and to prevent such incidents."
One security guard crashed into Paris Saint-Germain striker Goncalo Ramos while trying to stop a pitch invader reaching Ronaldo.
Portugal coach Roberto Martinez said it was lucky that the supporters who ran on to the pitch were only trying to take photographs.
"It is a concern because today we were lucky that the intentions of the fans were good," said Martinez.
"It is a very difficult moment if those intentions are wrong... probably we should give a message to the fans that it is not the right way."
UEFA said any spectators entering the field of play will be thrown out of the stadium, be banned for further matches and face "the filing of a formal criminal complaint for trespass".
Portugal qualified for the last 16 with their comfortable win over Turkey as Group F winners.