The sale of the Leopard-2 tanks had been billed as one of the biggest deals for the German armaments industry, Bild reported.
But Economy Minister Sigmar Gabriel, a Social Democrat in the left-right "grand coalition", has "positioned himself against a tanks delivery to the autocratic royal house", it said, citing government sources.
"Without agreement from the economy minister the deal has no chance," Bild said.
The report said the deal had not been sent to the German national security council, which counts Chancellor Angela Merkel among its members, for approval.
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Its latest report today said that Saudi Arabia had been chasing the German tanks for years and had budgeted nearly USD 25 billion for them.
The Leopard-2 tanks, Germany's main battle tank, is also produced under licence in Spain.
For decades Germany declined to sell heavy weapons to Saudi Arabia because of concerns over human rights and fears for Israel's security.
Contacted by AFP, an economy ministry spokeswoman said the government did not give information about "individual procedural stages of possible approvals for export of munitions".