The German Foreign Office has called on all German nationals in Iran to leave the country.
At the same time, it warned against travelling to Iran.
"The current tensions in the region, particularly between Israel and Iran, harbour the risk of a sudden escalation," the Federal Foreign Office announced on Friday evening.
The security situation can deteriorate quickly and without warning, the Foreign Office in Berlin advised.
"It cannot be ruled out that an escalation could also affect air, land and sea transport routes, with corresponding possible restrictions on entry and exit to Iran," it continued.
US President Joe Biden said on Friday that he expected an attack to happen "sooner rather than later."
However, he declined to comment on intelligence information.
At the beginning of April, two brigadier generals and five other members of Iran's powerful Islamic Revolutionary Guards (IRGC) were killed in a suspected Israeli airstrike on the Iranian embassy compound in the Syrian capital Damascus.
The Iranian leadership has since threatened to retaliate several times.