A coalition representing television makers charged yesterday that foreign manufacturers are skirting anti-dumping rules by shipping picture tubes to Mexico for assembly and import to the United States.

The Committee to Preserve American Color Television asked the Commerce Department to impose duties to stop the dumping of the color picture tubes, which the coalition said are entering the United States inside television sets made in Mexico.

Two years ago, the Commerce Department ruled that Japan, Korea, Singapore and Canada were ''dumping'' picture tubes on the U.S. market.

Dumping, the sale of goods at less than fair market value, occurs when the sale price of goods in the importing country is lower than the price in the exporting country.

Since the department's finding, imports of televisions from Mexico have increased 139 percent, the group said, while the volume of imported color televisions from the Far East has dropped significantly.

Jerry Pearlman, chairman of Glenview, Ill.-based Zenith Electronics Corp., said the ability of U.S. television manufacturers to compete profitably has been severely limited by what he called ''diversionary tactics'' of foreign manufacturers.

Color television imports from Japan dwindled to less than 320,000 last year from 4.3 million in 1985. During the same period, imports from Mexico increased to 3.9 million from about 138,000, according to the coalition.

''Imports did not increase because Mexican manufacturers recently developed a television-manufacturing industry,'' the group said.

''Rather, foreign manufacturers who are currently subject to anti-dumping duty orders covering color picture tubes and color televisions have discovered a new means of evading payment of anti-dumping duties.''

Imports of color picture tubes to the United States from Japan decreased to 122,301 last year from 500,615 in 1985. Imported tubes from Korea have decreased to about 22,000 last year from 776,255 in 1985.

''Those tubes are merely incorporated into color television receivers at screwdriver-type assembly plants {in Mexico} and then shipped to the United States,'' the group said.

Iva Wilson, president of Philips Display Components, an Ann Arbor, Mich., maker of large-screen color picture tubes, called for a complete investigation of the alleged tube diversion.