Iraq's outgoing prime minister said on Wednesday it was up to the next government to see through the parliament's decision to oust US troops.

Prime Minister Adel Abdul Mahdi's comments came ahead of planned protests against the American military presence in Iraq called for by an influential cleric.

Washington has responded to Iraq's requests to initiate troop withdrawals with blunt refusal.

Read more: US rejects Iraq request to discuss troop withdrawal

And on Wednesday, US officials said the US military is resuming operations against militants in Iraq and is working to soon restart training Iraqi forces.

The officials spoke on the condition of anonymity to discuss decisions not yet made public.

Meanwhile, Qatar said it was seeking to play a mediating role amid escalating tensions following a US drone strike that killed a top Iranian general in Baghdad.

Abdul Mahdi's government is in caretaker status following his resignation in December under pressure from mass demonstrations.

"I request that the president, parliament and political parties nominate a new prime minister, a new government that has full authority because these difficult, complicated circumstances, especially with pulling of the troops [...] that needs a government with full authority so it can go forward," Abdul Mahdi said in comments aired Wednesday from a cabinet session the previous day.

The US strike prompted Iraq's parliament to pass a non-binding resolution requesting the government end the presence of American troops in the country.

Abdul Mahdi has stood by the resolution despite signs of de-escalating tensions between Washington and Tehran.

Iran retaliated for the killing by hitting two military bases hosting US troops but did not cause casualties.

Read more: US-Iran conflict: Before and after the killing of Gen Soleimani

Last week, Abdul Mahdi asked US Secretary of State Mike Pompeo to work out a road map for an American troop withdrawal, but Washington responded saying the two sides should instead discuss how to recommit to their partnership.

Abdul Mahdi's recent remarks suggest he is keen on maintaining good relations with Washington yet firm that US troops must leave.

"I am determined to keep our friendships with all. They all helped us, they all scarified for us, some with blood, some with financial aid in fighting (the Islamic State group),” he said.

"We also respect the parliament's decision and we are working on implementing it in the right manner that guarantees Iraq's sovereignty."

Meanwhile, followers of influential cleric Moqtada Al Sadr acted on his call for millions to take to the streets to demonstrate against the American troop presence by announcing planned protests to take place next week, according to a statement circulating on social media verified by two activists.

The protests are expected to take place on Jan 24, according to the statement.

The cleric, who also leads the Sairoon bloc in parliament, derives much of his political capital through grassroots mobilisation.

Activists in Tahrir Square, the epicentre of a four month anti-government protest movement, said they feared the demonstrations would spark clashes.

"We are afraid that he will decide to start the protests in Tahrir," said Mustafa, an activist who gave only his first name fearing reprisals. "In this case there would be big issues with the Tahrir demonstrators."

Meanwhile, Qatar's Foreign Minister Mohammed bin Abdulrahman Al Thani, said the Gulf country was making contacts with regional and international countries in order to de-escalate regional tensions.

His visit to Iraq comes days after Qatar's Emir Sheikh Tamim bin Hamad Al Thani visited Tehran.

"Qatar, together with some friendly countries, is trying to decrease tensions. We have made international contacts for more consultations with our brotherly and sisterly countries," Al Thani said in a joint press conference with Iraq's Foreign Affairs Minister Mohammed al-Hakim.

Al Thani met with Iraqi Prime Minister Adel Abdul-Mahdi and President Barham Saleh later Wednesday.

"We discussed ways of decreasing tensions in our region and we have our common efforts and joint efforts together with our friends in Iran and America and our talks," said Al Hakim.