A spokesperson for the Muslim Brotherhood has criticised the visit to Egypt of US Deputy Secretary of State William Burns.
On Monday, Burns met army chief Abdel-Fattah El-Sisi, whom the Brotherhood accuses of leading a coup against ousted president Mohamed Morsi.
Morsi was deposed by the military on 3 July after millions of protesters took to the street calling for his removal and early presidential elections.
Brotherhood spokesperson Gehad El-Haddad said the US had failed to "stand up for principles" as they had done with ousted president Hosni Mubarak in 2011.
The US had granted the "coup" against Egypt's "first democratically elected president" the "legitimacy of recognition and continued military aide," El-Haddad said via Twitter.
There has been a debate in Washington over whether to cut the annual $1.5 billion in aid to Egypt because US law obligates the government to cut aid if a coup overthrows an elected leader. So far, the US has avoided calling Morsi's removal a coup.
Burns said the US administration was keen to ensure a peaceful democratic transition in Egypt through elections and dialogue between rival political factions.
El-Haddad responded by saying that "talk of inclusion and tolerance falls on deaf ears as arbitrary arrests [by the army] and the murder of peaceful protesters continues."
Morsi supporters have been camped out at protest sites in Cairo and Giza since his ouster. The army killed over 50 Morsi supporters at the Republican Guard headquarters on 8 July.
"Either the US is complicit in planning/executing the military coup or have come to welcome it," El-Haddad added.
"Does Burns really believe anyone in Egypt trusts him? No one trusts Mr Obama and Mr Burns," leading Brotherhood figure Essam El-Erian told CNN.
"Parliament was dissolved, the constitution has been suspended and the elected president was deposed, how are we to trust Burns," El-Erian asked, saying the Brotherhood would continue to protest.
After Morsi's deposition, the army suspended the constitution and dissolved the Islamist-dominated Shura Council (upper house of parliament).
It also announced a roadmap that was jointly drawn up with the opposition. It includes making amendments to the current constitution – a key opposition demand – and presidential and parliamentary elections.
A new cabinet is being formed by liberal economist Hazem El-Beblawi who was appointed prime minister by interim president Adly Mansour.
The Brotherhood and Morsi supporters are demanding that Morsi and the Shura Council be reinstated and the constitution restored before they engage in talks.
The Brotherhood – many of whose members have been arrested – has refused to join dialogue talks called for by the presidency.