East European leaders pledged continuing support for Vietnam yesterday, using anniversary celebrations in Hanoi as a spring-board for new attacks against China. Hungarian, Bulgarian, Czechoslovak and Polish leaders and official newspapers joined the Kremlin in sending warm greetings to Hanoi. They attacked Peking for allegedly exerting political and military pressure against the Hanoi government.

Communist Party chief Janos Kadar and other Hungariam leaders, in a cable on the 33rd anniversary of Communist rule in Hanoi, praised Vietnamese efforts to safeguard national independence "in the face of undisguised external pressure and attacks."

At a friendship rady in Budapest, officials "indignantly condemned armed provocations and bloody attacks" against Vietnam from China and Cambodia, the Hungarian news agency reported.

From Warsaw, party leader Edward Gierek expressed solidarity with Vietnam "against great power and begemonist pressure."

The official Polish newspaper Trybuna Ludu made it clear the message was aimed at Peking. "The Chinese leadership tries to hamper the peaceful work of the Vietnamese nation by its hegemonist and expansionist policy," an editorial said.

In Sofia, the official daily Rabotnichesko Delo accused China of "rude encroachments" against Vietnam. In Prague, the party newspaper Rude Pravo said Chinese leaders were mounting "gross pressure" against Hanoi.

Romainia was the only Soviet bloc country to salute Vietnam without attacking the Chinese.