Washington warned against travel to Egypt after an American was among three people killed during rival demonstrations for and against Islamist President Mohamed Morsi.
President Barack Obama spoke to Turkish Prime Minister Recep Tayyip Erdogan on Monday about the importance of free expression, following days of violence in anti-government demonstrations.
Turkish police used tear gas, rubber bullets and water cannon as they dispersed several thousand demonstrators who had gathered anew in central Istanbul in the latest flare-up of protests.
Three car bombs, including a suicide attack, a mortar round and a shooting killed at least seven people Sunday, most of them in northern Iraq where analysts fear tensions could trigger all-out conflict.
Syria's civil war has caused a split within Hamas over whether to cling to Shiite backers Damascus, Tehran and Hezbollah or side with Sunni allies such as Qatar, Egypt and Turkey.
Brazil's two biggest cities on Wednesday rolled back transit fare hikes that had triggered massive protests as demonstrators clashed with police outside a Confederations Cup match.
Thousands of protesters are expected on the streets of Belfast to urge G8 leaders to act on global poverty, although the issue looks likely to be overshadowed by concerns over the Syria conflict.
The United States dramatically toughened its stance on Syria on Thursday, accusing Bashar al-Assad of using chemical weapons against his people and promising "military support" to rebel forces.
Police fired tear gas and rubber bullets to disperse an angry crowd in a town on the outskirts of Paris where clashes erupted on Wednesday night after they questioned a woman wearing a full facial veil, which is banned in France.
At least 60 Shiite villagers died in clashes with rebels in eastern Syria while twin suicide bombings hit Damascus as the West moved to support the opposition following battlefield losses against pro-regime forces.
Taliban militants launched a grenade and gun attack on Kabul airport early Monday, taking over two nearby buildings which security forces attempted to storm as blasts and shooting rocked the Afghan capital.
Turkish PM Recep Tayyip Erdogan called for an immediate end to mass protests against his rule Friday, but urged supporters to "go home" after they staged a major show of strength welcoming him back from an overseas trip.
The US on Wednesday condemned a Hezbollah-backed assault on the town of Qusayr, as France kept up the pressure for action over what it said was the regime's use of sarin gas.
France said Tuesday it had proof President Bashar al-Assad's regime has used the deadly nerve agent sarin gas in Syria's civil war, adding that "all options," including armed intervention, are on the table.