Abraham, 22, had said he had "not made a decision yet" on his worldwide future as he is also eligible to play for Nigeria, having only played for England in two friendlies and not a competitive game.
"I respect it, Kyle respects it, Gareth does what he does for the national team".
'The opportunity they've been given by Frank Lampard has been fabulous, ' said Southgate.
Meanwhile, Everton midfielder Fabian Delph is recalled to the squad after a decent start to the season. Red Devils defender Aaron Wan-Bissaka also was not selected due to injury.
"There's still an emphasis on the development of younger players but surrounded by good experience".
Through four matches - all wins - England sits atop Group A, three points ahead of the Czechs who've played one more match. I haven't made a decision yet.
Elsewhere, Callum Wilson, Harry Kane and Marcus Rashford continue as England's strike force, with the latest addition of Abraham.
"There have been some hard decisions to make", he said.
Abraham has netted eight goals in 10 games in all competitions for Chelsea so far this season and is joint second in the Premier League's top-scorers' chart.
"He came as an incredible, outstanding player and he still is, physicality strong and fast, we try to help him since we're together to be a better player".