"I don't even want to think about it, that would be a disaster, it would simply mean the destruction of Europe," Mariano Rajoy said during an interview with radio Onda Cero when asked about the possibility of Le Pen or the AfD winning power.
"Mrs Le Pen has announced plans for a referendum. She wants (France) to leave Europe, as if Europe were the source of all misfortunes. I would like it if she visited the rest of the world," he added.
The National Front presidential candidate has promised if elected in May to dump the euro and organise a Brexit-style referendum on France's membership in the European Union.
"This is not going to happen. I am convinced that things will turn out alright in Germany and I am absolutely convinced there won't be a problem in France," said Rajoy, before adding he hopes conservative nominee Francois Fillon will win the French election.
"It is essential for the future of Europe that the elections in Germany and France go well," he said.
France's presidential election will be held on April 23 and May 7. While most opinion polls predict Le Pen will make it to the election's second round in May, they see her losing that run-off.
In Germany the AfD's anti-immigrant, eurosceptic rhetoric has won support among voters worried about the influx of more than a million migrants in the past two years.
With polls putting it on 12-15 percent, the party is tipped to win seats in the federal parliament for the first time in September's national election.