Jerusalem — Israeli citizens are seeking to assure themselves that their government was right to annex the Golan Heights and risk strained relations with the United States.
At the government press office, an ardent supporter of the ruling Likud Party drew a deep breath Dec. 21 and commented: ''Wow, (Prime Minister Menachem) Begin really used tough words with the Reagan administration. I think maybe he had to - but I wonder if he really thought out the consequences of this Golan thing before he acted. I don't think he expected the American reaction to be what it was.''
Moments later at a press conference, Foreign Ministry legal adviser Elyakim Rubenstein was maneuvering cautiously over Israel's legal justification for annexing the Golan Heights last week.
''No private rights (of Arab citizens of the Golan) have been changed or prejudiced,'' Mr. Rubenstein argued. ''The legal situation has been elevated.''
He contended that, while Syrian law applied to the Golan prior to its capture in 1967, it was rarely enforced. This caused a ''legal vacuum'' into which Israel came - first with a military government and now with a civil one. He dismissed charges that Israel had violated international law by unilaterally changing the status of occupied territory.
''International law is subject to reasonable time and conduct,'' Mr. Rubenstein said. ''Syria has passed in our view these reasonable conduct and time limits by announcing time and again it will not negotiate with or recognize Israel. . . . Even the Law of Occupation cannot be relied upon too long. . . . Good faith is necessary.''
Getting the most attention in the Israeli press, however, is the subject of greatly strained relations between the United States and Israel over the Golan issue. The Jerusalem Post in a Dec. 21 editorial termed Israel's Golan bill a ''provocation'' and said the ''punishing rebuke administered by the US was hardly surprising.'' It added that there was ''a touch of sheer insanity'' to Mr. Begin's charges the US was ''treating Israel like a vassal or like a banana republic.''
In a companion editorial, the Post called the Golan annexation ''a pointless assertion of sovereignty'' and said the economic fallout could be severe for Israel. By canceling the memorandum of understanding on strategic cooperation, Israel sets aside a $200 million military trade deal with the United States.
A motion was introduced in the Knesset Dec. 21 calling for a vote of no confidence in the Begin government over its handling of relations with the United States. But it is expected that Begin will weather the challenge.
But Foreign Minister Yitzhak Shamir, speaking on Israeli television, argued that it was not his government that ''went too far - someone else went too far. This method of punishing Israel like this is insulting, demeaning, and should be stopped.''
Mr. Shamir was referring to the Reagan administration's earlier suspension of the strategic cooperation agreement. The foreign minister admitted that his government ''did not anticipate that (US reaction to the Golan law) would come precisely in this form.''
A well-informed Western diplomat agreed the Begin government was indeed surprised by the American reaction. He said there was still some nervousness in the West that Israel might ''react to the reaction'' by military force, possibly in Lebanon.
But this diplomat pointed out that while the US-Israeli cooperation pact has been abandoned - at least for the moment - it was only a codification of agreements between the two countries, and the policies stand regardless.