Protesters in Morocco's commercial capital chanted "Freedom for Palestine," "If we don't speak out, who will?" and "No to normalization," and many wore keffiyeh scarves or waved Palestinian flags.
The North African kingdom established diplomatic ties with Israel in late 2020 under the US-brokered Abraham Accords which saw similar moves by the United Arab Emirates and Bahrain.
Under the deal, the United States recognized Morocco's claim to sovereignty over the disputed territory of Western Sahara.
Since the Israel-Hamas war in the Gaza Strip began on October 7, large-scale demonstrations in Morocco have called for the abrogation of the normalization accord.
On Sunday, the demonstrators marched through central Casablanca in a protest called by a grouping of leftist parties and Islamist movements.
"I cannot remain indifferent and silent in the face of what is happening to the Palestinians who are being killed on a daily basis," demonstrator Zahra Bensoukar, 43, told AFP.
Idriss Amer, 48, said he was protesting "in solidarity with the Palestinian people, against the Zionist massacre in Gaza and against normalization" of ties with Israel.
Rabat has officially denounced what it said were "flagrant violations of the provisions of international law" by Israel in its war against Hamas, but has not given any indication that normalization with Israel would be undone.
The Gaza war broke out after Hamas on October 7 launched an unprecedented attack on Israel which resulted in the deaths of more than 1,170 people, mostly civilians, according to an AFP tally based on Israeli official figures.
Israel's retaliatory offensive has killed at least 35,456 people in Gaza, also mostly civilians, according to data provided by the Hamas-run territory's health ministry.
Hamas also took about 250 hostages on October 7, of whom 124 remain held in Gaza including 37 the Israeli military says are dead.
CASABLANCA—Thousands of Moroccans demonstrated Sunday in Casablanca in support of the Palestinian people and against ties with Israel, an AFP journalist said, more than seven months into the Gaza war.