United Nations, N.Y. — The French Socialist government's policy on Africa is gradually falling more into line with that of the Reagan administration. In theory, France's ''new African policy'' is still diametrically opposed to the United States strategy. Whereas Washington stresses the countering of Soviet influence in Africa, France ''opposes the introduction of East-West rivalries into the third world,'' as Foreign Minister Claude Cheysson has stated many times. And this policy is applied particularly to Africa.
In fact, however, France has shifted gear in recent months and adopted a more conservative, traditionalist stance vis-a-vis its former African colonies than the one the Socialists had at first advocated.
The latest indicator of this change has been the resignation of Minister of Cooperation Jean-Pierre Cot in January. In charge of ''African affairs,'' Mr. Cot was a man deeply committed to changing the very nature of Franco-African relations from neocolonial to genuinely cooperative.
According to well-placed French analysts, his departure shows clearly that the ''realists'' have won the battle for President Mitterrand's heart over the ''idealists.'' There are even persistent rumors of an impending French deal with South Africa involving nuclear fuel.
In the words of one high French official, ''French short-term interests are once again being given priority over ideological considerations.''
A well-placed Socialist official admits: ''France can never be Sweden. It cannot escape the fact that it is a global power, with worldwide strategic and economic interests, closely interwoven with those of the United States and of Great Britain.''
France's Socialist government's turnabout in Africa has become evident as:
* In recent months, President Mitterrand has warmly embraced Gabon's President Omar Bongo and Morocco's King Hassan II. Gabon's authoritarian regime and capitalist ways had made the West African nation a target of French Socialist scorn. Morocco's ruler was not popular with many Socialists who criticized him for acting as what they described as an American stooge in Africa. However, France has announced it may now again sell sophisticated military equipment to Morocco and perhaps assist it with nuclear technology for peaceful uses.
* France has given up the Socialist idea of providing economic assistance for specific development projects in its former colonies. Under Presidents de Gaulle , Pompidou, and Giscard d'Estaing France aided the local governments directly - even though they were often considered tyrannical and corrupt. This method has been resumed. Critics of the latest switch also say that aid now is concentrated on the modern sector alone, thus opening up local market possibilities for French exports as much as possible.
* The idea of helping the smaller, poorer, French-speaking African countries as much as the larger, strategically more important ones, has been abandoned. Today the lion's share of French assistance goes to Senegal and Cameroon, the two most important countries in geopolitical terms.
* Relations with Africa have been moved back under the aegis of the Elysee (the French equivalent of the White House) rather than the Quai d'Orsay (the foreign relations ministry). Under de Gaulle and Pompidou, presidential assistant Jacques Foccart ruled French Africa with an iron fist. Secret funds and legions of secret agents were his preferred instruments of a largely neocolonial policy. ''Foccartism'' became anathema to the Socialists. Today, presidential adviser Guy Penne, in effect, has stepped into Foccart's shoes.
* Inside the ''contact group'' - the five Western nations (the US, Britain, Canada, West Germany, and France) who mediate between the United Nations and South Africa on Namibia's (South-West Africa) independence - France has stopped distancing itself from its partners as it did in the early months of the new Socialist government. Officially, France still says that there is no link between Namibia's right to independence and any withdrawal of Cuban troops from Angola. But whereas France previously threatened to leave the contact group if it did not rapidly lead to Namibia's independence, it now acquiesces discreetly in American unilateral efforts to work out a compromise between South Africa and Angola, according to informed sources.