The United States might accept an interim agreement on medium-range missiles in Europe, but only if it leads to the ''zero option'' proposed by President Reagan, Defense Secretary Caspar Weinberger said.
Weinberger said the administration might support such a plan ''if the first paragraph was that immediately following the signing of this interim agreement we would reconvene to negotiate a final stage, which is zero.''
Over the weekend West German Chancellor Helmut Kohl said it is time for President Reagan to propose an interim agreement at US-Soviet talks to reduce medium-range nuclear missiles in Europe.
The chancellor said the Reagan government would not have to give up its zero option, under which the US would not deploy cruise and Pershing II missiles in exchange for Soviet removal of SS-20 and other missiles from Europe. Mr. Kohl said the recent show of support for his government at the polls does not lessen the need for an agreement in the Geneva arms talks.
During a trip to Europe last month, US Vice-President George Bush said European leaders told him privately that they favor an ''interim solution,'' with reduced numbers of Soviet and US missiles deployed if the zero option fails before the 1983 NATO deployment deadline.