Desperate to avoid the turmoil that toppled leaders in Tunisia and Egypt, authorities have already announced some changes to placate demands that King Mohammed cede more powers and limit the monarchy's extensive business influence.
Some 10,000 people joined the protest in Casablanca, the largest city in one of the West's staunchest Arab allies. Marchers in the capital Rabat also denounced corruption and torture as well as unemployment, very high among youths.
Policing has been low-key for protests by the February 20 Movement, named after the date of its first march, particularly compared to the turmoil elsewhere in North Africa.
|People gather for a protest in Casablanca April 24, 2011.|
"This is more about the young ones than it is about us," said Redouane Mellouk, who had brought his 8 year-old son Mohamed Amine, carrying a placard demanding "A New Morocco."
"Our parents could not talk to us about political issues. They were too afraid. This must change," said Mellouk.
Although levels of popular anger have risen, ratings agencies assess Morocco as the country in the region least likely to become embroiled in the type of unrest that toppled Tunisian and Egyptian regimes and led to the conflict in Libya.
In Rabat, several thousand people marched through poor districts with high levels of unemployment and away from the center, where the previous monthly demonstrations have been held. There was no sign of trouble.
A 74 year-old man in Casablanca who gave his name only as Ahmed said Morocco's youths were right to protest.
"Look at them. They are educated and like most young educated Moroccans, they are idle," he said. "Everything in this country is done through privileges. You need an uncle or a relative somewhere to get somewhere."
Morocco is a constitutional monarchy with an elected parliament, but the constitution empowers the king to dissolve the legislature, impose a state of emergency and have a decisive say in government appointments.
King Mohammed last month announced constitutional reforms to give up some of his powers and make the judiciary independent, but protesters want more.
There is also resentment at the royal family's business interests through its holding company SNI.
One of the banners waved by the Casablanca marchers depicted the King's holdings as an octopus with tentacles stretching out to subsidiary companies. "Either money or power," it said.
Islamists also joined in the protests, demanding the release of all political prisoners. Authorities freed 92 political prisoners, most of whom were members of the Islamist Salafist Jihad group, earlier this month.
In Rabat, the wife of Islamist Bouchta Charef, who has said he was tortured in prison while accused of terrorism, called for all Islamists to be freed.
"They have made my children homeless," Zehour Dabdoubu told Reuters. "Every month I move from one house to another. I'm persecuted because people think I am the wife of a terrorist."
The banned Islamist opposition group Al Adl Wal Ihsane has maintained a low profile at the February 20 demonstrations, but said it supports them.
"It's excellent what's happening in Morocco. It's a quiet revolution," Nadia Yassine, daughter of the movement's founder, told Reuters by telephone. "We're moving slowly but surely."