The official's comments also come as Pakistan is trying to avoid being put on a global watch list over terrorism financing that could hamper its ability to receive foreign investment.
"The Pakistanis have wanted to appear responsive," the official said on condition of anonymity, sketching out the need for increased pressure.
US cooperation necessary for fight against terrorism: Mamnoon Hussain
"They have done the bare minimum to appear responsive to our requests," the official added, citing the need to prod the Taliban toward the negotiating table and round-up militants.
"We continue to make very specific requests, and when provided with very specific information they have responded, but we have not seen them pro-actively take the steps that we expect and know they are capable of."
It is more than 200 days since President Donald Trump announced America's latest strategy to win the long war in Afghanistan, focusing on pushing the Taliban to the negotiating table.
The plan demanded Pakistan move against Taliban leaders who support a continuation of the war, under the threat of cutting US military assistance and Afghanistan coalition funding to Islamabad.
So far, the strategy has borne only limited fruit, limiting the Taliban's march on the battlefield.
NAB summons envoy-designate to US Ali Jahangir in embezzlement case
But, according to Washington, there is little sign that Islamabad has made a decision to end its support for group which the country's powerful security services see as safeguarding its interests and against bulwark against Indian influence in Kabul.
"We are prepared to take steps that we think are necessary to safeguard US personnel and interests in the region," the official said, declining comment on what those steps would be, and on deadlines for action.
"We are continuing to look for real action, not just words, from Pakistan on the Taliban and Haqqani sanctuaries," the official said.
"We didn't think this would be easy," the official said. "We need to sustain the pressure."
"I don't think that we can just the efficacy of the strategy right now. We should give it more time, it deserves more time," the official added, suggesting an August anniversary of Trump's strategy speech may be a good time to reflect.
Members of the Financial Action Task Force (FATF), an anti money-laundering watchdog based Paris, voted last month to place Pakistan on its grey list of nations which are not doing enough to combat terror financing in June, reportedly under US pressure.
That gives Pakistan three months to make enough changes to avoid the listing.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ