The Belfast Telegraph said there had been no reports the blasts had inflicted injuries, though at least one pipe bomb detonated near police.
Police responded by turning water cannons on the demonstrators and firing a single plastic bullet, the newspaper said.
Hundreds more police officers were expected to be deployed in Northern Ireland from forces across England, Scotland and Wales, the Telegraph said.
"We will probably bring more mutual aid officers to continue through the week and to continue for as long as it is necessary," Will Kerr, assistant chief constable for the Police Service of Northern Ireland, said.
"The chief constable has made it very, very clear we will have as many resources on the streets of Belfast for as long as it takes to protect communities and our officers across Northern Ireland."
The newspaper said 44 officers had been injured and about 50 people had been arrested during the riots.
The trouble in Belfast began after the Parades Commission banned an Orange Order parade from moving through the nationalist district of Ardoyne Friday.
U.S. Vice President Joe Biden spoke with Northern Ireland representatives Monday on building support for a united community in that country, the White House said.
In a readout of the telephone conversation, the White House said Biden spoke with First Minister Peter Robinson and Deputy First Minister Martin McGuinness about the start of an All-Party Group process to address "sensitive issues such as parades and protests; flags, symbols and emblems; and dealing with the past."
Biden also expressed concern at parade-related violence and attacks on police in Belfast, and supported calls for calm and respect for rule of law.
The U.S. government, along with the British and Irish governments, will keep in contact with the chairman of the All-Party Group process, said Richard Haass, a former U.S. special envoy to Northern Ireland, as he "assists the political parties of Northern Ireland in the crucial work of healing the divisions of the past and building a truly shared future," the readout said.
Tackling sensitive issues to create a lasting peace "will require political courage, creativity, and compromise on the part of all Northern Ireland's political parties," the White House said. "We welcome the launch of the All-Party process as a necessary step toward building a united community."
In Belfast, authorities said hundreds of people may be charged with offenses arising from Belfast violence, RTE reported.
The Orange Order has faced growing pressure to provide the names of members who attacked police, the Belfast Telegraph said.
Peter Sheridan, former assistant chief constable and now head of the non-profit Cooperation Ireland, said the Orange Order must help to identify the offenders.
"If we really want to deal with the violence then, as difficult as it will be for them, morally and ethically that is what's required," he told the Telegraph.
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