The unions that represent D.c. government employes, frustrated in their efforts to force Mayor Marion Barry's administration into salary negotiations, said yesterday that they would oppose Barry's re-election in 1982.

William Simons, head of the Washington Teachers' Union and chief negotiator for the coalition of 14 public employe unions, said the unions would "mobilize an action program among union members with an eye toward the 1982 election. If the mayor and City Council are insensitive to labor in this city, we intend to bring them a message in two years which will be unmistakably clear: they can be replaced."

About 31,000 city workers are scheduled to receive next month a 5 percent salary increase, retroactive to Oct. 1, but the unions have been demanding that the city either give them the same 9.1 percent that federal workers got or engage in collective bargaining. Barry refused to do either, saying there was no more money available that the collective bargaining provisions of the new city employment law cannot take effect until next year.

The D.c. Public Employee Relations Board (PERB) directed to mayor to bargain this year, but he declined and appealed the PERB ruling to the courts. Nor, Simons said, the unions also will go to court, claiming that in the absence of collective bargaining they are entitled by law to parity with federal workers.

"The primary issue is collective bargaining," Simons told a press conference outside Barry's office. "Without collective bargaining, the despot who gaves can also take away."

Besides the court action and the political campaign, he said, the unions are also planning a public-relations effort to support their cause and an appeal to Congress for more funds for city workers. He said the unions would pursue "all legal avenues," which would eliminate a strike. Simons said he would never, in principle, forgo the possibility of "job action," but a strike would be illegal.