Morocco's official news agency said the man was stabbed on Saturday as he left his home in the city of Meknes, 140 km east of the capital Rabat.
The motive for the killing was not immediately known.
The head of the Moroccan Israelite Community Association said the victim was a 75-year old pensioner.
The latest killing came after two hooded men on Thursday shot dead Albert Rebibo in the city of Casablanca.
Rebibo's murder was the first killing of a Jewish citizen in Morocco.
But since Rebibo's murder occurred on the second anniversary of the September 11 attacks, some Moroccan Jews suspected it to be a part of a sinister plot.
The latest killing came after two hooded men on Thursday shot dead Albert Rebibo in the city of Casablanca
"Not only the Jewish community is targeted by these attacks but the whole of Morocco," a senior government official said.
Until the 1950s, Morocco was home to one of the largest Jewish communities. But now they total less than 5,000, after a massive exodus to Israel.
Meanwhile, a Moroccan court has sentenced 20 Islamists to prison terms of between three and ten years for 'extremist' activities.
Their sentences by a court in Rabat followed a spate of trials in Morocco of people suspected to be Islamist with links to banned groups.
Four of the convicted men were sentenced to 10 years in prison while 15 others got eight year jail terms.
They were all convicted of of "forming a criminal group with the aim of carrying out terrorist acts."
Another man was given a three-year sentence for "excusing terrorist acts and belonging to an unrecognised association."