Prime Minister Pierre Trudeau proposed a new Canadian constitution today in a move to reassure tense Quebec Province that the "deep aspiration" of its French-speaking majority would be secured in the new charter.

Trudeau made the announcement in a nationally televised speech hours after young Quebec nationalists, embittered by their defeat in yesterday's provincial referendum on sovereignty, marched on a predominantly English-speaking residential neighborhood here breaking windows, destroying mailboxes and throwing rocks at cars.

Spurred by shouts of "Let's go west, that's where the English are," about 3,000 separatist militants invaded Westmount, the wealthy neighborhood that is the symbol of English-speaking commercial power in this city, and clashed with riot police. At least eight persons were reported seriously injured.

Other nationalist demonstrations throughout the night were largely peaceful except when a crowd of 2,000 militants pulled down a flag pole, burned the Canadian flag, and began smashing shop windows along St. Catherine Street in the heart of Montreal early today.

The crowd chanted "Death to the English" and "FLQ, save our souls," the latter a reference to a terrorist separatist group that carried out bombings and kidnapings in the late 1960s and in 1970.

The disturbances, which were quickly brought under control, seemed to be the final cathartic acts of disappointed supporters of Premier Rene Levesque's separatist Parti Quebecois, whose bid to negotiate withdrawal from the Candian federation was rejected by 59.5 percent of Quebec voters yesterday.

Speaking French, Trudeau appealed to Quebecers to respect the will of the majority and asserted that their "deep aspirations can be accomplished through other means."

He vowed that a "brand-new constitution" would replace the British North American Act, an 1867 charter adopted by the British Parliament that is Canada's present constitution. He announced that he would send Finance Minister Jean Chretien, who, like Trudeau, is a native of Quebec, to begin exploratory talks with the premiers of all provinces in an effort to seek common ground for the new constitution.

In what seemed like a shift in his own long-held position, Trudeau hinted that he was willing to give provinces greater autonomy at the expense of the federal government.

Trudeau said his government has only two preconditions. One is that Canada will remain a true federation with its federal Parliament retaining "real powers." The other is that the new charter includes a bill of rights and freedoms including the provision securing French linguistic rights.

"For us, everything else is negotiable," he said.

He also challenged Levesque to "participate in good faith, loyalty, in the development of new federalism." Quebec's Liberal opposition leader Claude Ryan issued a similar challenge earlier today when he called for new provincial elections, although Levesque's term does not expire until November 1981.

"Having chosen their constitutional future within Canadian federalism, the voters of Quebec should be given an opportunity to choose their bargaining agents" in the forthcoming constitutional talks, Ryan said.

The prevailing view here is that the impressive victory of federalist forces has, for the time being, checked the threat of Quebec's secession. But the victory was purchased with large and vague promises from Trudeau, Ryan and key English-speaking Canadian politicians.

The redemption of these promises causes more concern for the winners than the losers. Analysts aruge that there is a long distance between accepting the need for change and making specific changes acceptable to all the disparate provinces in this vast country.

Moreover, there are disagreements in the federalist camp, with Trudeau favoring a stronger central government and Ryan insisting that the provinces be "sovereign and autonomous in their fields of jurisdiction."

Although he had bitterly denounced Levesque's sovereignty-association proposal, Ryan seems closer to the policies of his opponent except in his belief that his goals can be accomplished within the Canadian federation.

Quebec's basic demands include greater autonomy in the fields of health and welfare services and in communications.

In other provinces, especially those in the resource-rich western Canada, the main issue is control over provincial wealth.

At this stage, the ball seems to be in the federalist court. They have won an impressive victory largely on the promises that "real changes" would take place soon." The margin of victory was due to the English-speaking minority, which comprises 20 percent of Quebec's 6.3 million people.

Levesque, who won 40.6 percent backing in the referendum, received slightly less than 50 percent of the French-speaking vote. A Canadian Broadcasting Corporation analysis revealed another important factor: among voters 40 years and older, Levesque pulled 27 percent of the vote against Ryan's 73 percent, but the reverse was true among younger voters. v

The desire for an independent Quebec is also exceptionally strong among the better-educated, professionals, and intellectuals. For many of them, acceptance of yesterday's vote in any final sense is very difficult. As television commentator Gail Scott said this morning, "How can you build a country when all the poets are against you?"

It is uncertain how Levesque and his party will conduct their talks on the new constitution or whether the defeat yesterday would lead to internal splits among the separatists.

In spite of cries "Until next time!" from his supporters last night, Levesque has urged the party to accept the defeat and give Ottawa and English-speaking Canada "another chance" to redress Quebec's grievances.