Gundogan, 25, last played for Germany in a friendly against France on Nov. 13.
England's players received a motivational postcard from Sam Allardyce two days after he had left his job as national team manager.
Iniesta missed last month's international wins against Belgium and Liechtenstein with a knee injury but has since returned to fitness.
Wayne Rooney will remain as England captain under interim manager Gareth Southgate, according to multiple reports.
Cristiano Ronaldo returns as one of four changes to the Portugal squad for their World Cup qualifiers against Andorra and the Faroe Islands.
Coleman, who led Wales to the Euro 2016 semifinals, said he was "gutted" for Sam Allardyce, who lost his job after just 67 days.