Chelsea full-back Marcos Alonso recently revealed he would no longer be taking the knee before matches, with the Spain international saying the gesture is "losing a bit of strength".
Players in Premier League teams have been taking the knee before games since matches resumed in June 2020 after the United Kingdom's first coronavirus-enforced lockdown, in the aftermath of the unlawful police killing of George Floyd in Minneapolis the previous month, which sparked protests against racial injustice across the globe.
Some players, such as Crystal Palace's Wilfried Zaha, have since elected not to take the knee, though the majority of teams and players in the top flight still do so.
However, Lukaku - who was the subject of racist abuse during his time with Inter in Serie A - has now joined his team-mate Alonso in doubting the strength of the gesture.
"I think we can take stronger positions, basically," Lukaku said. "Yes, we are taking the knee, but in the end, everybody’s clapping but, sometimes after the game, you see another insult."
Lukaku added that social media executives must take the lead in tackling online hate.
"The captains of every team, and four or five players, like the big personalities of every team, should have a meeting with the CEOs of Instagram and governments and the FA and the PFA, and we should just sit around the table and have a big meeting about it," Lukaku said.
"I have to fight, because I'm not fighting only for myself. I'm fighting for my son, for my future kids, for my brother, for all of the other players and their kids, you know, for everybody.
"At the end of the day, football should be an enjoyable game. You cannot kill the game by discrimination. That should never happen."