Speaking at a meeting of the Women and Democracy Foundation (KADEM) in Istanbul, Erdogan accused Germany of repeating past Nazi habits.
"They do not let our friends speak in Germany. Let them do it. Do you think that barring a Turkish minister from pronouncing a speech [in Germany] will make the votes 'No' instead of 'Yes'?" Erdogan said.
"Germany! You have nothing to do with democracy. Your recent practices are no different than the Nazi ones of the past," he added.
On Thursday, the municipality of Gaggenau in southwest Germany revoked its permission for Turkish Justice Minister Bekir Bozdag's meeting, citing concerns about overcrowding. This prompted Bozdag to cancel his planned visit to Germany altogether.
Economy Minister Nihat Zeybekci’s planned address on Sunday to a Turkish community in the western city of Cologne was also cancelled by local authorities over security concerns.
The move drew strong criticism from the Turkish government and opposition parties alike.Ties between Ankara and Berlin have been strained in recent months. Turkish leaders have criticized their German counterparts for turning a blind eye to terrorist organizations such as the PKK and FETO, which they say use Germany for their activities targeting Turkey.
Tensions between the two countries further escalated last week after German media and politicians sharply criticized Turkey for the pre-trial detention of Die Welt’s Istanbul correspondent Deniz Yucel on charges of terror propaganda.
Among Germany’s 3 million-strong Turkish community, nearly 1.5 million of them are eligible to vote. They will cast their votes at Turkish consulates in Germany between March 27 and April 9.