The Three Lions, who are currently fourth in Fifa’s rankings, take on North Macedonia in their final Euro 2024 qualifier on Monday.
England have already qualified for the tournament in Germany and a draw would guarantee they are among the top seeds.
“If you’re going to be the top-ranked team, there’s no room for sloppiness or casualness,” said Southgate.
“If we’re going to be a top team then the level of performance has got to be spot on every time.”
World Cup winners Argentina are currently top of the rankings with France second and Brazil third, while England have spent five consecutive years inside the top five.
The Three Lions could rise to third in the world, leapfrogging Brazil, when the next update is announced on 30 November – but Southgate wants to reach the summit.
“Am I driven by being ranked number one? Yes, because ultimately you achieve that through consistency and you’ve got to play well in the tournaments as well because the ranking points are higher in the tournaments,” said Southgate.
“Also, it sets behaviours every day on the training pitch, off the training pitch.
“With the games at the weekend, we might be ranked third in the world at the minute, but we’re two places off where we need to be so we can’t waste games.”
Seven players named in the original squad for this round of qualifiers have now pulled out with Jude Bellingham, Levi Colwill, James Maddison, Callum Wilson and Lewis Dunk also absent.
But Southgate said competition for places in the squad was high and time was running out for players to prove themselves.
“There’s some things we’d like to see. Some of the players have got three games to get into a squad, some have got maybe three to get into a team, maybe a couple more if we’re talking about the team,” Southgate said.
The 53-year-old suggested talk of the Euros tournament itself might have become a distraction following England’s lacklustre 2-0 victory over Malta on Friday.
“I feel almost as if we’ve almost talked too much about the Euros already and I didn’t see our focus in the right place at the weekend,” he said.
“So, it’s Monday, then it’s March, then it’s the summer. And we go from there.”