The US has been trying to convince Pakistani officials that the fight against militants is one that Islamabad needs to be engaged in and that Pakistan's stability is at stake, says the BBC's Kim Ghattas in Washington.
Saturday's bombing will have given that message a dramatic sense of urgency, and the US is watching closely to see how Islamabad deals with the aftermath, our correspondent says.
A little known Pakistani militant group, Fidayeen-e-Islam, has said it carried out the attack, which left 53 dead and more than 266 injured.
The group - based in Pakistan's tribal areas and connected to leading militant Baitullah Mehsud - told the BBC that the aim of the attack was to stop US interference in Pakistan.
Pakistan's government has promised raids in some "hotspots" near the Afghan border.
But the US would like to see Pakistan take a more aggressive military approach on the ground, and rethink its unpopular peace deals with the militants, our correspondent says.
Pakistan has seen new outbreaks of violence since the hotel bombing:
A suicide bomber killed nine troops in the Madiyan area of the volatile Swat valley of north-west Pakistan. It was unclear who was responsible
Troops reportedly fired on US helicopters that violated Pakistani airspace near the border with Afghanistan on Sunday night
In Peshawar, capital of North West Frontier Province, an Afghan diplomat was kidnapped and his driver killed, reports say.
The heavily guarded hotel was attacked at about 2000 (1500 GMT). CCTV footage showed a lorry ramming the security barrier at the hotel gate moments before the blast.
The BBC's Damian Grammaticas tours the site of the bomb attack
The bomb - believed to have been detonated in the lorry - left a six-metre (20ft) crater.
Conflicting accounts have emerged in Pakistan about who should have been in the Marriott hotel on the night of the attack.
The top official in Pakistan's interior ministry said a dinner to be attended by the president, prime minister and military leaders had been cancelled at the last minute.
But hotel owner Sadruddin Hashwani told the BBC there never was a booking for a government dinner that night nor any plans for a government function.
Meanwhile, the group claiming responsibility said its aim was to kick "American crusaders" out of Pakistan.
It said 250 US marines had been killed in the attack, together with many officials from Nato and other countries involved in attacks on Muslim interests in Pakistan and Afghanistan.
However, almost all of the dead were Pakistanis. The Czech ambassador to Pakistan, one Vietnamese, a German and an American were among the dead, with an American and a Danish intelligence officer missing, presumed dead.
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