The department's spokesman has refused to criticise Pakistan for saying it would look for other options if a deal for buying eight F-16 fighter jets from the US fails.
"These are sovereign decisions that nations make with respect to their defence needs, and it's up to Pakistan... how they'll fulfil their defence needs," Dawn online on Thursday quoted spokesman John Kirby as saying.
Kirby made the remarks when asked whether Islamabad's relations with the US would come under strain if Pakistan bought fighter jets from China.
"As for the relationship, as I've said many, many times, it's an important one. It's critical; it's vital in that -- particularly in that part of the world; and it's a relationship we have absolutely no intention of losing focus on or diminishing in any way," he said.
"But these are obviously sovereign decisions that Pakistan has to make."
After being asked about a Pakistani minister describing the US aid as "peanuts", Kirby said: "I would just simply say that, again, it's an important relationship. We're going to continue to support that relationship."
Kirby defended the assistance the US has provided to Pakistan despite strong opposition from certain lobbies in Congress.
Last week, Congress prevented the US administration from subsidising the $700 million F-16 deal.
Under the arrangement, Pakistan was to pay $270 million for the eight aircraft while the US was to provide about $430 million from its foreign military financing facility.
Pakistan has expressed its inability to pay the entire amount.