Pacific Islands Forum leaders are set to meet with United States President Joe Biden next month as Washington aims to accelerate its diplomatic efforts to counter China's presence in the region.

The US deputy Secretary of State, Wendy Sherman - who is on a whirlwind Pacific tour - has confirmed President Biden is "looking forward to welcoming" Pacific leaders to the White House in September, which will coincide with the week of the United Nations' General Assembly.

Sherman said the exact date for the meeting will be announced "very soon".

She arrived in Samoa on Thursday for a brief visit and was in Tonga before flying to Solomon Islands for the 80th anniversary commemorations of the of the Battle of Guadalcanal.

Samoa's Prime Minister, Fiame Naomi Mata'afa, commended the United States for rejoining the Paris Agreement on climate change whilst Sherman praised Samoa for sharing common democratic values.

In Tonga, Sherman had an audience with King Tupou VI.

She signed off on an energy grant of $US100,000 for the Kingdom.

Meanwhile, in Washington, Fiji's Prime Minister Frank Binimarama met with Vice President Kamala Harris.

Harris tweeted it was "all in the spirit of partnership, friendship and respect".

Mr Bainimarama tweeted he's looking forward to a "Pacific Leaders' summit at the White House soon."