It was the second protest in as many days against the de facto Saudi ruler, who was expected to fly into Tunis from Egypt on Tuesday for talks with President Beji Caid Essebsi.
He had held talks on Sunday with King Hamad. Bob Menendez are working on to sanction the Crown Prince.
Mohammed's visit is part of a tour of several Arab countries, his first trip overseas since Khashoggi - a sharp critic of Mohammed - was killed inside a Saudi consulate in Turkey on October 2, triggering global condemnations.
But he said that among the issues that had not been investigated under the Republican leadership of the House "is whether the Russians have been laundering money through the president's businesses and this is the financial hold that the Russians may have".
The UK has also been blasted for its continued arms sales to Saudi Arabia as it conducts its brutal war in Yemen.
Travelling overseas for the first time since the killing, the crown prince is visiting allies in the Middle East before heading to a Group of 20 summit in Argentina this week, where he may face questions about the gruesome slaying.
"While Saudi Arabia is a strategic ally, the behavior of the Crown Prince - in multiple ways - has shown disrespect for the relationship and made him, in my view, beyond toxic", Graham said on Tuesday.
US senator disagrees with Trump over CIA's Khashoggi assessment
A Senate aide said Haspel is not scheduled to be involved in Wednesday's briefing, which will take place at 11 a.m. EST.
The crown prince has found a backer in President Donald Trump, who has called the Khashoggi murder abhorrent but stressed bin Salman's denials of complicity as well as the interdependent economic relationship between the USA and Saudi Arabia.
His killing was blamed on the Israeli national intelligence agency Mossad.
But many Tunisians are angry over the killing and suspicions of the prince's involvement.
Cornyn also said he thought the Senate would vote on a Yemen resolution introduced by Senator Bernie Sanders seeking to pull back any USA support for the Saudi-led war in Yemen.
Tunisian officials stressed the "historical and fraternal" relations between Tunis and Riyadh, adding that the region would suffer if Saudi Arabia, a regional power, was destabilised by Prince Mohammed's removal.