At the same time, Mattis also lauded India's commitment towards the development in Afghanistan.
Trump, while announcing the new strategy for Afghanistan, had accused Pakistan of harbouring "agents of chaos" and providing safe havens to militant groups waging an insurgency against the US-backed government in Kabul.
But, Mattis during a visit to Kabul said the new strategy was "not exclusive of someone".
It is inclusive for all responsible states that want to stop terrorism in its tracks and defend the innocent, he said.
"I agree 100 per cent with President Ghani that this South Asia strategy and this renewed commitment is an opportunity for Pakistan to engage in the counter terror campaign," Mattis told reporters at a joint news conference with Afghan President Ashraf Ghan, according to a Pentagon transcript.
Mattis said that the United States would "watch" Islamabad's choices.
Ghani echoed Mattis' views.
This is primarily because for the first time, the United States seeks to hold Pakistan accountable for its support to terrorist groups and organisation.
Trump's also policy seeks greater developmental role for India in this war-torn country.
NATO Secretary General Jens Stoltenberg agreed with both Mattis and Ghani, saying that this is a regional approach, which includes both Pakistan and India.
Both of them have to be included in a mutual approach.
He urged all countries in the region to support an Afghan-led and Afghan-owned peace process.
Mattis said India has been "very, very generous" in its development assistance to Afghanistan.
India is committed to doing even more to help the people of Afghanistan, he said.
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)