Soviet authorities are stepping up efforts to curtail contacts between Soviet citizens and foreigners in an apparently broad drive to counter Western influences here.

The moves range from physical attempts to bar Westerners from contacting political dissidents and Jewish activists to a propaganda campaign designed to warn the population to stay away from foreigners in general and Americans in particular.

The tightening up seems to be a rejoinder to President Reagan's call during the summer for a worldwide crusade against communism but it appeared to have ushered a climate in which the most hard-line elements in Soviet ruling circles are becoming increasively assertive.

Well-informed observers here said the general tightening up is directly tied to the turmoil in Poland. Poland has frightened the Communist Party here, according to this view, not so much in terms of how to resolve the crisis there but rather as an example of what could happen in any socialist country once it becomes too open to foreign capital, ideas, books, culture and journalists.

A variety of things during the past two months suggest a decidedly harsher policy toward all contacts with the West:

* A new regulation went into effect last month that requires special permission for the mailing to the West of official Soviet publications and books. Previously these were mailed normally after being inspected at a local post office.

* A Canadian parliamentary delegation including former foreign minister Flora MacDonald were roughed up in Leningrad when they attempted to visit Jewish families that have been denied exit visas to Israel.

* Galina Barats, the wife of an imprisoned human rights activist, was kept practically under house arrest when she sought to meet Western journalists. When they went to her home, they were turned away by a plainclothesman who said the Barats affair is an "internal Soviet matter" and no business of Western media.

* Journalists were barred by members of the Soviet political police, the KGB, from meeting a small group of pacifists. One member of the unofficial "peace" committee, Oleg Radzinsky, 24, was arrested last week on anti-Soviet charges. Its leader, Sergei Batovrin, 25, was released recently after a month in a psychiatric hospital.

* Andrei Sakharov, the human rights activist and physicist banished to Gorki, has accused the KGB of having stolen his unpublished memoirs, diaries and other personal papers from his automobile. He was in the car at the time and he charged that KGB agents used a drug to stun him and make off with the documents and other personal effects.

Other signs of this new attitude include the termination of direct-dialing telephone links with the West and harassment of foreign diplomats and journalists. The latter range from acts of vandalism such as ripping off of hubcaps and puncturing tires to the denial of access to sources of information.

Pressure is being applied by and large on those in the society who seek contacts with foreigners or who attempt to make their dissenting views known to larger audiences.

The fact that the KGB last year contacted and interviewed Soviet citizens who had lived or studied in Poland or had some connection with that country suggests fears here of its infectious potential and efforts to nip it.

In a broader context, the media continue to focus on foreigners as "ideological enemies" who are trying to impose Western tastes and standards on the Soviet Union. The new chief of the KGB, Vitaly Fedorchuk, described in an article last year such attempts as subversive, saying their aim is to achieve a "spiritual decomposition" of the Soviet people.

The increasingly nationalistic tone of the media seems to have reached a peak in the latest issue of the monthly "Man and Law," a publication of the Ministry of Justice. In an article seeking to discourage Soviet women from marrying foreigners, the monthly carries a long article based on letters from expatriate Soviet women "who, on the basis of their bitter experiences, have been convinced of the priceless advantages of Soviet way of life."

The letters as recounted in the article tell about the misery of Soviet women who had gone abroad with their foreign husbands. The main theme is that love for a man is a temporary affair while love for the fatherland is eternal. "When your love is over you find out that only the fatherland stays with you forever," the article said.