The build-up to the Three Lions' chance of sealing Euro 2020 qualification in their 1,000th match was overshadowed by a skirmish at St George's Park on Monday.
Sterling made private and public apologies after emotions got the better of him less than 24 hours after clashing with Gomez towards the end of Manchester City's 3-1 loss at Premier League leaders Liverpool.
The 24-year-old was made to watch Thursday's match against Montenegro from the stands as punishment, with Harry Kane's hat-trick helping England seal a 7-0 win - their biggest at home since 1987 - and top spot in Group A.
Gomez was brought on as the Three Lions' final substitute in the second half at Wembley, where the defender was surprisingly jeered by pockets of supporters.
Sterling, who applauded his team-mate onto the field, posted on Twitter: "To all the England fans, I wanted to leave things as it was but tonight I have to speak again.
"It was hard for me to see my team-mate get booed for something that was my fault. Joe hasn't done anything wrong and for me to see someone who keeps his head down and work hard...
"Especially after a difficult week for him to be booed when he came on tonight was wrong. I've taken full responsibility and accepted the consequence. I felt as though I had to say this, get home safe everyone."
England manager Southgate echoed Sterling's sentiments in the post-match press conference.
"I don't know what more I could've said," he said. "Again, first and foremost, the whole dressing room are disappointed with it because the dressing room are tight, every one of them.
"Contrary to what I'm told has been said in various quarters, all of the players are united, the whole thing was put to bed the other day.
"Joe had done absolutely nothing wrong. No England player should ever be booed when they're wearing the shirt, ever. I don't get it.
"So, all of the players are particularly disappointed with that, and the reason that I wanted to get Joe on the pitch tonight was that he's been with us in September and October and we've not got him into the games.
"Also, I know I'm going to start Raheem on Sunday and get him back onto the pitch as well because it was important for both of them to get back on the field with England and show everybody that we're all in this now.
"So, yes, I'm hugely disappointed for him, but he's got the support of all of us - the whole dressing room, totally united. And we'll make sure we're there for him."
Asked whether he will speak to Gomez about the issue on Friday, Southgate said: "Absolutely. I've already started that, and yes, he's got to feel the support of everybody, which he has, completely."