Abdurahim al-Awadhi, assistant to the foreign minister for legal affairs, expressed "concern that [Uri] Brodsky has been released on bail and granted the freedom to return to Israel while the case against him continues," in a statement carried by the official WAM news agency.
A German court released the alleged Israeli agent on bail on Friday – he is suspected of links to the killing of Mahmud al-Mabhuh, a leader of the military wing of the Palestinian Islamist movement Hamas.
The Gulf country's foreign ministry "sought clarification today [Saturday] from the German government on the Brodsky case," according to the statement.
Awadhi said that his country "seeks assurances that Brodsky is in no way connected to the murder of Mahmud al-Mabhuh."
"As this may relate to a serious crime committed in Dubai, the UAE expects full and close cooperation from the German authorities and will continue to pursue the matter through diplomatic channels," the foreign ministry said.
Polish authorities arrested Brodsky in June at Warsaw airport before extraditing him to Germany on Thursday on suspicion of illegally obtaining a German passport under the name Michael Bodenheimer that was later found to have been used by a member of the hit squad which killed Mabhuh.
The squad which Dubai police believe was from Israel's intelligence agency Mossad was found to have used 26 doctored foreign passports, sparking a diplomatic rumpus not only with Germany but also with Australia, Britain, France and Ireland.
Israel has said there is no evidence linking it to the assassination.