"We now have to watch out that we don't miss the right moment, that we get a grip on the tensions that have emerged recently," he said at Berlin's former Checkpoint Charlie border crossing, an iconic Cold War site.
Gorbachev -- who is set to meet Chancellor Angela Merkel during his visit -- stressed the importance of good relations between Moscow and Berlin, which has been a key interlocutor in the Ukraine standoff.
"And we have learned from the past that when Russians and Germans understand each other ... When our relationship is good, then everyone is well off, not just our two peoples.
"That means, we should be careful it stays that way."
Moscow is locked in a confrontation with the West over its support for separatists in neighbouring Ukraine, with Washington and Brussels imposing several rounds of sanctions on Russia.
Gorbachev said yesterday he would seek to defend President Vladimir Putin's policies while in Germany, saying he was "absolutely convinced that Putin protects Russia's interests better than anyone else".
His policies of glasnost and perestroika (openness and restructuring), earned him admiration in the West and the 1990 Nobel Peace Prize, but disdain from many of his countrymen who blame him for ending the Soviet Union.
Gorbachev, greeted with cheers at the Berlin event, was asked to place his hands into a wet plaster cast bolted onto an original piece of the Wall, which opened 25 years ago on Sunday.
Dressed in simple blue jeans and a coat, he was humble about his role in the momentous events, telling a crowd of onlookers, tourists and journalists that "I am proud I could contribute a little bit to fact that we live like this today".
"I remember a gloomy, shattered city, the scars of the drama we all experienced. They were the marks of the great and bloody war," he said.
