The German government had previously confirmed that eight of the ten victims initial were German, but the two extra deaths bring the total number of victims to twelve.
A married couple from Mainz in Rhineland-Palatinate were among the victims of the suicide attack which killed ten people plus the attacker in the Sultanahmet area of the city, public broadcaster ARD reports.
A further victim was a man from Bad Kreuznach, also in the western state. His wife survived but was seriously injured.
A married couple from Brandenburg were also among the dead, as Germany counted one of the highest ever tolls of Bundesrepublik citizens in a single terrorist attack.
The victims were all on a tour of three countries in the Middle East run by a Berlin company which offers adventure to people “in the best years of their life.”
Nine further Germans were seriously injured in the attacks.
“The terrorists are enemies of all free people, indeed their enemies of all humanity,” Chancellor Angela Merkel said in response to the attacks.
“But exactly this freedom, along with our determination in cooperation with international partners to tackle the terrorist will prevail,” she added.
Aimed at Germans?
According to eyewitnesses, the suicide bomber behind the attack aimed specifically for where the German tourists were.
Security expert Bruno Schirra told Bild on Wednesday that Isis had warned after terror attacks in Tunisia last June that the group would ensure Germans "could no longer holiday safely all around the Mediterranean".
"The Islamists hope for a heightening of the conflict of the majority in German society with Muslims, in the knowledge that this will drive more fighters into their arms," Schirra said.
"I think it's no co-incidence that Isis sought out a German tour group for this attack," Turkey expert Günter Seufert agreed on ARD television on Tuesday evening, saying that the terrorists hope to stoke division at home in Germany.
However, speaking at a press conference in Istanbul on Wednesday morning Interior Minister Thomas de Maizière said that there no indication that Germans had been specifically targeted.
De Maizière had travelled to the Turkish city specifically to assess the situation after the terrorist attack.
British expert David Lewin told Bild that "Germans are no more and no less in Isis' sights than British people or Americans or citizens of other western countries."
The main thing about attacking tourists, Lewin argued, is that they make for an easy target for terrorist attackers compared with - for example - heavily-defended government buildings or airports.
According to Turkish authorities the terrorist was a 27-year-old with links to Isis who had travelled from Syria to Turkey shortly beforehand.
Conflicting reports emerging from Turkish media suggest the man came from Saudi Arabia.
Isis however has not taken responsibility for the attack.