Anwar said while it was not wrong to have ties with Washington, it is another matter when one becomes a 'yes-man' and endorse the US's treatment of the Muslim world.
"Let me state that it is not wrong to have good ties with America, but to bend over and support its policies on Iran and its actions in Afghanistan amounts to a treachery against the Muslims and against this country.
"What is the PM's stance over Iran?" he asked.
Anwar, speaking at the Dewan Rakyat during the debate on supplementary budget for the foreign ministry, was responding to an earlier statement by Pasir Salak MP, Tajuddin Abdul Rahman, that the Permatang Pauh MP wielded influence among American officials.
Najib, during a meeting with US president Barack Obama earlier this week, was reported to have agreed with Washington's campaign to isolate Iran over its nuclear power project. He was also quoted by a White House statement as saying that Malaysia was prepared to cooperate with the US in Afghanistan for "capacity building" through the training of police, military personnel and civilian administrators.
'I'm not a slave to US'
"It is acceptable to state that Iran should not use nuclear arms, but having said that, what about Israel? Why Najib did not have the courage to criticise Israel and went on bended knees by speaking out against Iran in the White House?"
Anwar also said that Malaysia had welcome Obama's decision to withdraw troops from Afghanistan and had been opposed to US intervention in the country from the very beginning.
"Now Najib says he wants to do training in Afghanistan. What sort of training when Muslims are being killed in Afghanistan?" asked Anwar.
He added that while he welcome cordial ties with the US, "I would not bend over and become a slave to the US," he stressed.
Washington has been leading efforts to toughen sanctions on Iran over its nuclear programme, which the US and Western allies say is aimed at producing weapons, a charge Tehran has consistently denied. The US efforts have however met with strong opposition from big powers such as China, Russia, Latin-American countries and Turkey. UN security council members Brazil, Turkey and Lebanon, alongside permanent member China, are expected to oppose the next round of sanctions against Iran.